PR libstdc++/80064
	* include/bits/stl_heap.h (__is_heap, push_heap, __adjust_heap)
	(pop_heap, make_heap, sort_heap, is_heap_until, is_heap): Cope with
	invalid instantiations using function types for _Compare argument.
	* testsuite/25_algorithms/make_heap/80064.cc: New test.

From-SVN: r246197