re PR c++/18143 (Duplicated thunk with a huge member in the hierarchy)

re PR c++/18143 (Duplicated thunk with a huge member in the hierarchy)

.:	* tree.c (tree_check_failed): Emit general error if the list of
	node types is empty.
cp:
	PR c++/18143
	* cp-tree.h (NON_THUNK_FUNCTION_CHECK, THUNK_FUNCTION_CHECK): New.
	(struct lang_decl_flags): Add thunk_p flag.
	(struct lang_decl): Remove separate fixed_offset. Place
	cloned_function and fixed_offset into union.
	(DECL_CLONED_FUNCTION_P, DECL_CLONED_FUNCTION): Adjust.
	(DECL_THUNK_P, SET_DECL_THUNK_P): Adjust.
	(THUNK_FIXED_OFFSET): Adjust.
	* method.c (make_thunk): Adjust.

From-SVN: r90399