invoke (Wnon-virtual-dtor): Update to match implementation.

	* doc/invoke (Wnon-virtual-dtor): Update to match implementation.
	(Weffc++): Likewise.

	cp/
	* class.c (check_bases_and_members): Warn about non-virtual dtors
	in public bases only.  Check warn_ecpp before complaining about
	non-polymorphic bases.

	testsuite/
	* g++.dg/warn/Wnvdtor-2.C: Add more cases.
	* g++.dg/warn/Wnvdtor-3.C: Likewise.
	* g++.dg/warn/Wnvdtor-4.C: Likewise.

From-SVN: r209212