TOOL FOR CONNECTING AMMUNITION BELTS The invention relates to the technical field of tools for connecting linked ammunition belts and ammunition compartments comprising such tools. Ammunition for automatic weapons firing in bursts is commonly supplied in ammunition in the form of so-called linked ammunition belts, that is to say, where each piece of ammunition is connected to at least one adjacent piece of ammunition by means of at least one link. When a first ammunition belt has been completely consumed, it is necessary to resupply the weapon using a second ammunition belt. In order to limit the frequency of this type of operation, it is known to connect ammunition belts to one another coming from different ammunition boxes so as to form a longer ammunition belt than that contained in a single magazine. Application FR 3,052,247 therefore shows a turret comprising several ammunition boxes arranged in magazines. A device or tool making it possible to connect the ammunition belts is described in patent application EP 1,691,164. This tool makes it possible to connect a first linked ammunition belt to a second linked ammunition belt owing to a piece of connecting ammunition. The piece of connecting ammunition is arranged on a mounting that longitudinally and radially sets it. In the case at hand, this is a tube in which the piece of ammunition is partially engaged by its ogive. A lever able to pivot relative to a mounting comprises a push member intended to push a first link of the first belt radially toward the piece of ammunition. The second link of the second belt is housed in the first link of the first belt and is also pushed radially toward the piece of ammunition. Once the links are pushed and clipped on the piece of ammunition, they are then coaxial to one another and to the piece of ammunition and thus connect the first end of the first belt to the second end of the second belt. Such an operation with such equipment is easy to perform in a spacious environment such as a workshop. However, the operation becomes impossible when the ammunition belts are in ammunition boxes, the boxes themselves being able to be housed in an ammunition compartment. Under these conditions, the narrowness makes the removal of the connecting device to difficult, if not impossible. Indeed, the tool described by patent EP 1,691,164 requires having access to the end of the projectile to be able to cap the piece of ammunition with the tool. The invention proposes to address this problem of conveniently implementing and removing the tool for operations to connect ammunition belts. Thus, the invention relates to a tool intended to connect an end of a first linked ammunition belt to an end of a second linked ammunition belt using a piece of connecting ammunition, the tool comprising at least one mounting intended to set the piece of connecting ammunition radially and longitudinally, the tool comprising a lever hingedly connected to the mounting, the lever comprising a push member intended to engage with at least one link of one end of the first belt and to push the at least one link radially relative to the piece of ammunition into a second position where the at least one link is coaxial to the piece of ammunition, the tool being characterized in that it comprises a frame secured to the mounting and able to be secured to a compartment containing an ammunition belt, the frame comprising first and second adjacent portions pivoting relative to one another about an axis parallel to the hinge of the lever so as to allow easy removal of the tool, the frame comprising a means for blocking the pivoting of the portions. Advantageously, the push member is also in contact with a second link of one end of the second belt. Advantageously, the lever comprises a retractable handle. The invention will be better understood upon reading the following disclosure, done in reference to the appended drawings, in which: Figure 1 shows a tool according to the invention in the open position. Figure 2 shows a tool according to the invention in the open position with two ammunition belts and one piece of connecting ammunition. 30 Figure 3 shows a tool according to the invention in the closed position with two ammunition belts and one piece of connecting ammunition. Figure 4 shows a tool according to the invention with its first and second portions pivoted relative to one another. Figure 5a shows a schematic cross-sectional view of an ammunition box equipped with a tool according to the invention during the connection of two ammunition belts. Figure 5b shows a schematic longitudinal sectional view of an ammunition box equipped with the tool according to the invention during the connection of two ammunition belts. Figure 5c shows a schematic cross-sectional view of an ammunition box equipped with a tool according to the invention, during its removal from the ammunition box. According to figure 1, a connecting tool 100 comprises a lever 1 hinged relative to a frame 2, the frame 2 comprising a mounting 3. The mounting 3 comprises two parallel strips 15 fastened to the frame 2 and on which indentations 16a and 16b are made that are intended to receive and position ammunition of the belt. It will be noted in the figure that each strip 15 comprises a median indentation 16a and two lateral indentations 16b and that the median indentation 16a is located lower than the lateral indentations 16b. The reasons for such an arrangement will be specified later. The frame 2 further comprises first and second portions 2a and 2b, which are adjacent and connected to one another by a hinge 4 able to pivot these portions relative to one another about an axis 4a that is parallel to the hinge 6 of the lever 1. A blocking means 9 allows or blocks the pivoting of the first and second portions 2a and 2b relative to one another. The lever 1 comprises a push member 7 arranged opposite its hinged end 6, as well as a maneuvering handle 8, the handle being retractable by pivoting relative to the lever 1 about an axis 17. 30 According to figure 2, one end of a first linked ammunition belt 10 as well as one end of a second linked ammunition belt 11 are arranged across the frame 2. A linked ammunition belt refers to a series of pieces of ammunition that are parallel to one another and connected to one another by links so as to form an ammunition belt. The end of the first ammunition belt 10 comprises an empty link 10a positioned coaxially to an empty link 11a of the end of the second ammunition belt 11 and above a piece of ammunition 12, called piece of connecting ammunition 12. Each link 10a and 11a comprises an opening that is oriented toward the piece of connecting ammunition 12. The piece of connecting ammunition 12 is set axially and radially by the central indentations 16a of the mounting 3 with which it cooperates and which are visible in figure 1. It will be noted that the mounting 3 comprises side indentations 16b that are located in the vicinity of the edges of the first portion 2a of the frame 2. These indentations cooperate with a piece of ammunition of each belt 10 and so as to set the belts 10 and 11 for convenience reasons to hold the belts 10 and in position across the frame. The push member 7 of the lever 1 is located in a first position where it interferes with the top of the empty links 10a and 11a of the belts and 11. The links are of the type described by patent EP 1,985,960. Each link includes a central yoke joint C and two side yoke joints L. The central yoke joint C of a link cooperates with the side yoke joints L of an adjacent link so as to form a pivot connection around each piece of ammunition. The empty link 10a of the first belt 10 is for example a central yoke joint C, and it will engage with the side yoke joints L of the empty link 11a of the second belt 11. The central yoke joint C of the empty link 10a is located below the side yoke joints L of the empty link 11a, the push member 7 bearing on the side yoke joints L therefore only with the empty link 11a, which will cause the clipping of the two links 10a and 11a on the piece of ammunition. Alternatively, for ammunition belts with a different structure, it will be possible to define a tool whereof the push member will be in contact with a single link or with two links to be attached. 30 Figure 3 shows that the push member 7 is located in a second position after the manual lowering of the lever 1 downward using the handle 8. By pushing downward in this way, the push member 7 has pushed, radially relative to the piece of connecting ammunition 12, the empty links 10a and 11a until they are placed coaxially to the piece of ammunition. Each empty link 10a and 11b is resilient enough to be able to allow the piece of connecting ammunition 12 to pass. Figure 1 shows that the blocking means 9, when it is engaged, connects the first portion 2a to the second portion 2b and keeps them in a same plane P. Conversely, according to figure 4, when the blocking means 9 is disengaged, in no longer connects the two portions 2a and 2b of the frame 2, which makes it possible to incline the first portion 2a relative to the second portion 2b. Thus, when the tool 100 is inserted into an ammunition box 14 as shown in figures 5a and 5b in order to connect two ammunition belts 10 and 11, it is possible, according to figure 5c, to pivot the first portion 2a relative to the second portion 2b in order to remove or insert the tool 100 easily below the ammunition belts 10 and 11 in order to connect them. The two belts 10 and 11 are then connected to one another simply, safely and effectively, even in a narrow environment like that of an ammunition box 14. 20