With Concepts, overloads of special member functions can differ in
constraints, and this paper clarifies how that affects class properties: if
a class has a more constrained trivial copy constructor and a less
constrained non-trivial copy constructor, it is still trivially copyable.

	* tree.c (special_memfn_p): New.
	* class.c (add_method): When overloading, hide ineligible special
	member fns.
	(check_methods): Set TYPE_HAS_COMPLEX_* here.
	* decl.c (grok_special_member_properties): Not here.
	* name-lookup.c (push_class_level_binding_1): Move overloaded
	functions case down, accept FUNCTION_DECL as target_decl.

From-SVN: r274534