PR c++/84850 - -Wclass-memaccess on a memcpy in a copy assignment operator with no nontrivial bases or members

gcc/cp/ChangeLog:

	PR c++/84850
	* call.c (first_non_public_field): New template and function.
	(first_non_trivial_field): New function.
	(maybe_warn_class_memaccess): Call them.

gcc/testsuite/ChangeLog:

	PR c++/84850
	* g++.dg/Wclass-memaccess-3.C: New test.
	* g++.dg/Wclass-memaccess-4.C: New test.

From-SVN: r258719