c-family/
	* c-common.c (max_constexpr_depth): New.
	* c-common.h: Declare it.
	* c-opts.c (c_common_handle_option): Set it.
	* c.opt (fconstexpr-depth): New option.
cp/
	* semantics.c (push_cx_call_context): Return bool.
	(cxx_eval_call_expression): Handle excess depth.

From-SVN: r171012