http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50196
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-08-26 16:06:00 UTC --- It would be possible to define _GLIBCXX_HAS_GTHREADS without _POSIX_TIMEOUTS, so that <thread> is available, and most of <mutex> too. I think only the Timed Mutex types require _POSIX_TIMEOUTS, so there's a lot of useful functionality that doesn't require it. We could have _GLIBCXX_HAS_GTHREADS and _GLIBCXX_HAS_TIMED_MUTEXES, with only the second depending on _POSIX_TIMEOUTS
