PR c++/61659
	PR c++/61687
Revert:
gcc/c-family/
	* c.opt (-fuse-all-virtuals): New.
gcc/cp/
	* decl2.c (mark_all_virtuals): New variable.
	(maybe_emit_vtables): Check it instead of flag_devirtualize.
	(cp_write_global_declarations): Set it and give helpful diagnostic
	if it introduces errors.
	* class.c (finish_struct_1): Check it.

From-SVN: r213308