PR libstdc++/64203
	* include/std/shared_mutex: Fix preprocessor conditions.
	* testsuite/experimental/feat-cxx14.cc: Check conditions.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch@218512 138bc75d-0d04-0410-961f-82ee72b054a4