arm: testsuite: correctly detect armv6t2 hardware for acle execution tests

arm: testsuite: correctly detect armv6t2 hardware for acle execution tests

Some of the ACLE tests for Arm are executable, but we were only testing
that the compiler could generate code for them, not that the hardware
was capable of executing them.  Fix this by adding an execution test for
suitable hardware.

gcc/testsuite:

	* lib/target-supports.exp (check_effective_target_arm_arch_v6t2_hw_ok):
	New function.
	* gcc.target/arm/acle/data-intrinsics-armv6.c: Use it.
	* gcc.target/arm/acle/data-intrinsics-rbit.c: Likewise.