constexpr.c (cxx_eval_constant_expression): Temporarily change input_location to CLEANUP_STMT location.

	* constexpr.c (cxx_eval_constant_expression) <case CLEANUP_STMT>:
	Temporarily change input_location to CLEANUP_STMT location.

	* g++.dg/cpp2a/constexpr-dtor3.C: Expect in 'constexpr' expansion of
	message on the line with variable declaration.
	* g++.dg/ext/constexpr-attr-cleanup1.C: Likewise.

From-SVN: r277320