Re: (ITS#7363) libmdb should use POSIX semaphores on non-apple BSD systems too.

Howard Chu writes:

PTHREAD_PROCESS_SHARED is defined just about everywhere, that's not a useful test. (You only discover at runtime that the mutex creation/init failed...)

Argh. Oh well, we should only do the namespace cleanup, then. __BSD__ symbols etc.

BTW, I think the lock file should contain a field indicating the sync primitive type, so different compilations of MDB won't use different sync primitives. Which maybe also means we might as well pick the primitive at runtime (try PTHREAD_PROCESS_SHARED first, then sem_open).