Fix cst segfault

The cst binary segfaults when run:

2023/06/14 12:31:48 ==== Sign U-Boot ====
[   11.662751] cst[373]: segfault at 0 ip 0000000000000000 sp 00007ffdb31d8ea8 error 14 in cst[5608bb418000+4000] likely on CPU 1 (core 1, socket 0)
[   11.669059] Code: Unable to access opcode bytes at 0xffffffffffffffd6.
2023/06/14 12:31:48 u-boot-dtb.imx" | Segmentation fault
2023/06/14 12:31:48 Action `Sign U-Boot` failed at stage Run, error: exit status 139
[   11.703889] EXT4-fs (vda1): unmounting filesystem.

Tweak binary creation to avoid rectify issue.

Fixes infrastructure/apertis-issues#352 (closed)

Signed-off-by: Martyn Welch martyn.welch@collabora.com