cp:
	* cp-tree.h (THUNK_TARGET): New macro.
	(THUNK_VIRTUAL_OFFSET): For result thunks it is always a binfo.
	(finish_thunk): Remove offset parms.
	* class.c (find_final_overrider): Look through thunks.
	(get_vcall_index): Use THUNK_TARGET.
	(update_vtable_entry_for_fn): Look through thunks. Set covariant
	fixed offset here. Adjust finish_thunk call.
	(build_vtbl_initializer): Adjust finish_thunk calls.
	* mangle.c (mangle_call_offset): Remove superfluous if.
	(mangle_thunk): Adjust.
	* method.c (make_thunk): Adjust.
	(finish_thunk): Adjust.
	(thunk_adjust): Remove assert.
	(use_thunk): Use THUNK_TARGET
	* dump1.c (cp_dump_tree): Adjust thunk dumping.
testsuite:
	* g++.dg/inherit/covariant5.C: New test.
	* g++.dg/inherit/covariant6.C: New test.
	* g++.dg/inherit/covariant7.C: New test.

From-SVN: r60628