class.c (dfs_find_final_overrider): Adjust so that the most derived object is a binfo, rather than a class type.

	* class.c (dfs_find_final_overrider): Adjust so that the most
	derived object is a binfo, rather than a class type.
	(find_final_overrider): Likewise.
	(add_vcall_offset_vtbl_entries_1): Simplify accordingly.
	(add_vcall_offset): Likewise.

	* g++.dg/abi/vcall1.C: New test.

From-SVN: r59104