arm: testsuite: improve compatibility of arm/lto/pr96939_1.c

This test overrides the architecture, but fails to specify the
floating point architecture.  This causes problems if -mfpu=auto is
used.

gcc/testsuite:

	* gcc.target/arm/lto/pr96939_1.c: Add +simd to the architecture
	specification.

gcc/testsuite/gcc.target/arm/lto/pr96939_1.c

 /* PR target/96939 */
-/* { dg-options "-march=armv8-a+crc" } */
+/* { dg-options "-march=armv8-a+simd+crc" } */
 
 #include <arm_acle.h>