bits/signum.h on ubuntu specifically says not to include directly anyway and the defines should be picked up when including bits/signal.h (they are on alpine linux at least)

at worst case, consider simply hardcoding?

{{raise(19) /* 19 = SIGSTOP */ }}

here?

https://github.com/mongodb/mongo-c-driver/blob/1.17.0/src/libmongoc/tests/test-mongoc-cache.c#L84