PR libstdc++/77864
	* include/bits/stl_map.h (map::map()): Use nothrow constructibility
	of comparison function in conditional noexcept.
	* include/bits/stl_multimap.h (multimap::multimap()): Likewise.
	* include/bits/stl_multiset.h (multiset::multiset()): Likewise.
	* include/bits/stl_set.h (set::set()): Likewise.
	* testsuite/23_containers/map/cons/noexcept_default_construct.cc:
	New test.
	* testsuite/23_containers/multimap/cons/noexcept_default_construct.cc:
	Likewise.
	* testsuite/23_containers/multiset/cons/noexcept_default_construct.cc:
	Likewise.
	* testsuite/23_containers/set/cons/noexcept_default_construct.cc:
	Likewise.

From-SVN: r240780