re PR libstdc++/84998 (std::hash<std::bitset<N>> fails in Debug Mode)

re PR libstdc++/84998 (std::hash<std::bitset<N>> fails in Debug Mode)

2018-03-20  François Dumont  <fdumont@gcc.gnu.org>

	PR libstdc++/84998
	* include/bits/stl_bvector.h: Fix std::hash friend declaration.
	* include/std/bitset: Likewise.
	* include/bits/stl_map.h (std::map<>): Fix _Rb_tree_merge_helper friend
	declaration.
	* include/bits/stl_multimap.h (std::multimap<>): Likewise.
	* include/bits/stl_multiset.h (std::multiset<>): Likewise.
	* include/bits/stl_set.h (std::set<>): Likewise.
	* include/bits/unordered_map.h (std::unordered_map<>): Fix
	_Hash_merge_helper friend declaration.
	(std::unordered_multimap<>): Likewise.
	* include/bits/unordered_set.h (std::unordered_set<>): Likewise.
	(std::unordered_multiset<>): Likewise.

From-SVN: r258693