S/390: Require a hardware vector support for test to succeed.

The test case works on S/390 too, but only with -march=z13 or later
(i.e. if Gcc can make use of hardware vector support).  Otherwise the
optimization gets too complex.  The attached patch forces Gcc to use
-march=z13 instead of xfail'ing the test on S/390.

gcc/testsuite/ChangeLog

	* gcc.dg/tree-ssa/ssa-dom-cse-2.c: Require a hardware vector support for
	test to succeed.

From-SVN: r232971

gcc/testsuite/ChangeLog

+2016-01-29  Dominik Vogt  <vogt@linux.vnet.ibm.com>
+
+	* gcc.dg/tree-ssa/ssa-dom-cse-2.c: Require a hardware vector
+	support for test to succeed.
+
 2016-01-29  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/69509

gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-cse-2.c

 /* { dg-do compile } */
 /* { dg-options "-O3 -fno-tree-fre -fno-tree-pre -fdump-tree-optimized --param sra-max-scalarization-size-Ospeed=32" } */
+/* S390 needs hardware vector support for this to work (the optimization gets
+ * too complex without it.
+ * { dg-additional-options "-march=z13" { target { s390*-*-* } } } */
+
 
 int
 foo ()