DR 1813
	PR c++/83374 - __is_standard_layout wrong for a class with repeated bases.
	* class.c (check_bases): Set CLASSTYPE_NON_STD_LAYOUT for a class if
	CLASSTYPE_REPEATED_BASE_P is true.

	* g++.dg/ext/is_std_layout3.C: New test.
	* g++.dg/ext/is_std_layout4.C: New test.

From-SVN: r273139