GNU mode FFI incorrectly applied in large workspace: `strerror_r` type mismatch

[l-monninger]

Summary

We've encountered a jemalloc-sys v0.5.4 a build issue on x86_64 summarized here. For some reason the FFI doesn't seem to be properly selecting between Posix and GNU Mode, hence causing type mismatches with the strerror_r method.

This is occurring in a workspace where we are attempting to join several others. I could see something like feature unification being a problem.

Any help is appreciated.