PowerPC: Support for SHA2 and SHA3 Compute Instructions (RFC02654)

opcodes/
	* ppc-opc.c: (insert_sr, extract_sr, insert_bl, extract_bl):
	New functions.
	(DMRATp, PADE, HASHT, HASHSR, PADID, PADBL, XSHAHASH, XSHA3HASH,
	XSHA2HASH, XX2PAD, XX2PADE, XSHAHASH_MASK, XSHA2HASH_MASK,
	XSHA3SR_MASK, XSHA3HASH_MASK, XX2PAD_MASK, XX2PADE_MASK): New defines.
	(OBF, PMSK8, L, RRWn, UIM): Update for new macros.
	(powerpc_opcodes): Add dmsha256hash, dmsha512hash, dmsha2hash,
	dmsha3dw, dmcryshash, dmsha3hash, dmxxsha3512pad, dmxxsha3384pad,
	dmxxsha3256pad, dmxxsha3224pad, dmxxshake256pad, dmxxshake128pad,
	dmxxsha384512pad, dmxxsha224256pad, dmxxshapad.

gas/
	* testsuite/gas/ppc/future.s: New test.
	* testsuite/gas/ppc/future.d: Likewise.