pthread_barrier_init threw for any non-null attributes object, and no
function could create one. Add pthread_barrierattr_init, _destroy,
_getpshared and _setpshared after FreeBSD libthr, and let
pthread_barrier_init take the object.
PTHREAD_PROCESS_SHARED still throws in pthread_barrierattr_setpshared:
FreeBSD 9.0 rejects it and 11.0 accepts it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
DotDebian