* include/debug/macros.h (__glibcxx_check_non_empty_range): Define.
	* include/debug/debug.h (__glibcxx_requires_non_empty_range): Define.
	* include/debug/formatter.h (__msg_non_empty_range): Add.
	* src/debug.cc: Message text for __msg_non_empty_range.
	* include/bits/stl_heap.h (pop_heap): Check for non-empty range.
	* testsuite/25_algorithms/pop_heap/empty_neg.cc: New.

From-SVN: r181970