PR c++/56930
	* call.c (convert_like_real): Use cp_convert_and_check.
	* cvt.c (cp_convert_and_check): Use maybe_constant_value.
	* semantics.c (cxx_eval_constant_expression): Handle LTGT_EXPR.
	(potential_constant_expression_1): Handle OMP_ATOMIC*.

From-SVN: r199232