c-decl.c (merge_decls): Kill different_binding_level and different_tu arguments; simplify throughout.

	* c-decl.c (merge_decls): Kill different_binding_level and
	different_tu arguments; simplify throughout.
	(duplicate_decls): Likewise.
	(pushdecl, merge_translation_unit_decls): Update calls to
	duplicate_decls.
testsuite:
	* gcc.dg/noncompile/20020213-1.c: Add another dg-warning line.

From-SVN: r76269