libstdc++: Suppress Doxygen docs for more implementation details

libstdc++: Suppress Doxygen docs for more implementation details

libstdc++-v3/ChangeLog:

	* include/bits/alloc_traits.h: Suppress doxygen documentation.
	* include/bits/allocated_ptr.h: Likewise.
	* include/bits/enable_special_members.h: Likewise.
	* include/bits/hashtable.h: Likewise.
	* include/bits/hashtable_policy.h: Likewise.
	* include/bits/uses_allocator.h: Likewise.
	* include/bits/node_handle.h: Document node handles and suppress
	documentation for protected members.
	* include/std/any: Suppress documentation for implementation
	details.