PR libstdc++/55847
	* src/c++11/shared_ptr.cc (bad_weak_ptr::what()): Correct string.
	* testsuite/20_util/shared_ptr/cons/weak_ptr_expired.cc: Verify
	string.

	PR libstdc++/55728
	* include/std/functional (bad_function_call::what()): Declare.
	* src/c++11/functional.cc (bad_function_call::what()): Define.
	* config/abi/pre/gnu.ver (bad_function_call::what()): Export.
	* testsuite/20_util/bad_function_call/what.cc: New.

From-SVN: r194958