arm: testsuite: improve compatibility of pragma_arch_attribute*.c

These tests use pragmas adn attributes to change the architecture.
Sometimes they simply add a feature using "+crc", but other times they
try to completely reset the architecture using "arch=armv8-a+crc".
The latter fails on a hard-float ABI with -mfpu=auto because it also
clears the FP capability.  Fix by adding +simd when the full
architecture is specified.

gcc/testsuite:

	* gcc.target/arm/pragma_arch_attribute.c: Add +simd to pragmas that
	set an explicit architecture.
	* gcc.target/arm/pragma_arch_attribute_2.c: Likewise.
	* gcc.target/arm/pragma_arch_attribute_3.c: Likewise.