[Bug libstdc++/50862] deadlock in std::condition_variable_any

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50862

--- Comment #16 from Jonathan Wakely <redi at gcc dot gnu.org> 2011-10-26 
14:06:12 UTC ---
Yes, thanks for spotting it.  Ideally we'd define this_thread::yield() anyway,
but until then the test should use the dg-require