PR c++/50296
	* semantics.c (register_constexpr_fundef): Call is_valid_constexpr_fn.
	(cx_check_missing_mem_inits): Handle bases and empty trivial members.
	(validate_constexpr_fundecl): Remove.
	* decl.c (start_preparsed_function): Don't call it.
	* cp-tree.h: Don't declare it.

From-SVN: r178604