re PR libstdc++/56002 ([C++11] allow generic locks to be used without requiring plattform support for threads)
PR libstdc++/56002
* include/std/mutex (lock_guard, unique_lock, lock): Define without
depending on _GLIBCXX_HAS_GTHREADS.
* testsuite/30_threads/lock_guard/cons/1.cc: Run on all targets.
From-SVN: r196706
