PowerPC: Add future hwcap2 bits

PowerPC: Add future hwcap2 bits

This patch adds support for the two new HWCAP2 fields used by the
__builtin_cpu_supports function.  It adds support in the target_clones
attribute for -mcpu=future.

The two new __builtin_cpu_supports tests are:
	__builtin_cpu_supports ("isa_3_1")
	__builtin_cpu_supports ("mma")

The bits used are the bits that the Linux kernel engineers will be using for
these new features.

testsuite/
2020-06-05  Michael Meissner  <meissner@linux.ibm.com>

	* gcc.target/powerpc/clone3.c: New test for using 'future' with
	the target_clones attribute.