[Bug libstdc++/50196] [C++0x] std::thread not available under macos

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50196

--- Comment #11 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-01-28 
19:08:47 UTC ---
I think I meant to say std::timed_mutex and std::recursive_timed_mutex