https://gcc.gnu.org/ml/gcc-patches/2018-10/msg02026.html
	gcc/cp/
	* cp-tree.h (OVL_DEDUP_P): New.
	* name-lookup.c (name_lookup::add_overload): Check OVL_DEDUP_P.
	(get_class_binding_direct): Likwise.
	* tree.c (ovl_make): Propagate OVL_DEDUP_P.
	(ovl_copy): Copy it.
	(ovl_insert): Do not keep using-decls ordered.
	(lookup_maybe_add): Adjust comment.

	gcc/testsuite/
	* g++.dg/lookup/using60.C: New.

From-SVN: r265679