* ppc-dis.c (powerpc_dialect): Handle power4 option.

	* ppc-dis.c (powerpc_dialect): Handle power4 option.
	* ppc-opc.c (insert_bdm): Correct description of "at" branch
	hints.  Test PPC_OPCODE_POWER4 to determine branch hint flavour.
	(extract_bdm, insert_bdp, extract_bdp, valid_bo): Likewise.
	(BOFM64, BOFP64, BOTM64, BOFP64): Rename to BOFM4, BOFP4 etc.
	(BODNZM64, BODNZP64, BODZM64, BODZP64): Likewise.
	(PPCCOM32, PPCCOM64): Delete.
	(NOPOWER4, POWER4): Define.
	(powerpc_opcodes): Replace occurences of PPCCOM32 with NOPOWER4,
	and PPCCOM4 with POWER4 so that "at" style branch hint opcodes
	are enabled for power4 rather than ppc64.