2016-10-05  Fritz Reese  <fritzoreese@gmail.com>

Fix ICE due to comparison between UNION components.

	gcc/fortran/
	* interface.c (gfc_compare_types): Don't compare BT_UNION components
	until we know they're both UNIONs.
	* interface.c (gfc_compare_union_types): Guard against empty
	components.

	gcc/testsuite/gfortran.dg/
	* dec_union_9.f90: New testcase.
	* dec_union_10.f90: New testcase.

From-SVN: r240810