[arm] Fix gcc.target/arm/xor-and.c

This test is naughty because it doesn't use the proper effective target checks
and add-options mechanisms for setting a Thumb1 target, which leads to Thumb1 hard-float errors
when testing a toolchain configured with --with-cpu=cortex-a15 --with-fpu=neon-vfpv4 --with-float=hard --with-mode=thumb.

This patch fixes that in the obvious way.

	* gcc.target/arm/xor-and.c: Fix armv6 effective target checks
	and options.

From-SVN: r256782

gcc/testsuite/ChangeLog

+2018-01-17  Kyrylo Tkachov <kyrylo.tkachov@arm.com>
+
+	* gcc.target/arm/xor-and.c: Fix armv6 effective target checks
+	and options.
+
 2018-01-17  Jakub Jelinek  <jakub@redhat.com>
 
 	PR rtl-optimization/83771

gcc/testsuite/gcc.target/arm/xor-and.c

 /* { dg-do compile } */
-/* { dg-options "-O -march=armv6" } */
-/* { dg-prune-output "switch .* conflicts with" } */
+/* { dg-require-effective-target arm_arch_v6_ok } */
+/* { dg-add-options arm_arch_v6 } */
+/* { dg-options "-O" }  */
 
 unsigned short foo (unsigned short x)
 {