[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 #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-08-27 
15:35:55 UTC ---
No, of course not.  That's not what I meant.

I mean we (the library maintainers) could define _GLIBCXX_HAS_GTHREADS in
c++config.h when gthreads is available, and not require _POSIX_TIMEOUTS