https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104027
--- Comment #4 from Arnaud Charlet <charlet at gcc dot gnu.org> --- Thanks for the report and investigation. The issue is actually caused by the introduction of a "ghost" (empty for code generation purposes) unit a-nbnbbig.ads, since the change you mentioned didn't change the existing call to exit(0), the issue was already there before, just never triggered in libgnat.so. Patch looks good to me, if you get a successful build and check-ada, it's preapproved.
