[Xcb] pthread_condattr_{init,destroy} stubs in libc?

[Matt Turner]

Context: https://bugs.freedesktop.org/show_bug.cgi?id=72074#c2

It looks like there was a patch from 2009 to add
pthread_condattr_{init,destroy} stubs to FreeBSD's libc. It doesn't
seem to have been committed, without any indication why not.

It would be much appreciated if a FreeBSD developer could sort this
out. It's been in multiple downstream bug trackers for years...