Fix PR c++/79360

gcc/cp/ChangeLog:

	PR c++/79360
	* typeck2.c (process_init_constructor_union): Consider only
	FIELD_DECLs when looking for an NSDMI.

gcc/testsuite/ChangeLog:

	PR c++/79360
	* g++.dg/cpp1y/nsdmi-union2.C: New test.

From-SVN: r245239