c-decl.c (diagnose_mismatched_decls): Give an error for redefining a typedef with variably modified type.

	* c-decl.c (diagnose_mismatched_decls): Give an error for
	redefining a typedef with variably modified type.

testsuite:
	* gcc.dg/c1x-typedef-1.c: Expect errors for redefinitions of
	variably modified typedefs.
	* gcc.dg/c1x-typedef-2.c: Remove.

From-SVN: r171172