Enable Intel WAITPKG instructions.

Enable Intel WAITPKG instructions.

Intel has disclosed a set of new instructions for Tremont processor.
The spec is
https://software.intel.com/en-us/intel-architecture-instruction-set-extensions-programming-reference
This patch enables Intel WAITPKG instructions.

gas/
	* config/tc-i386.c (cpu_arch): Add WAITPKG.
	(cpu_noarch): Likewise.
	* doc/c-i386.texi: Document WAITPKG.
	* i386/i386.exp: Run WAITPKG tests.
	* testsuite/gas/i386/waitpkg-intel.d: New test.
	* testsuite/gas/i386/waitpkg.d: Likewise.
	* testsuite/gas/i386/waitpkg.s: Likewise.
	* testsuite/gas/i386/x86-64-waitpkg-intel.d: Likewise.
	* testsuite/gas/i386/x86-64-waitpkg.d: Likewise.
	* testsuite/gas/i386/x86-64-waitpkg.s: Likewise.

opcodes/
	* i386-dis.c (enum): Add PREFIX_MOD_0_0FAE_REG_6,
	PREFIX_MOD_1_0FAE_REG_6.
	(va_mode): New.
	(OP_E_register): Use va_mode.
	* i386-dis-evex.h (prefix_table):
	New instructions (see prefixes above).
	* i386-gen.c (cpu_flag_init): Add WAITPKG.
	(cpu_flags): Likewise.
	* i386-opc.h (enum): Likewise.
	(i386_cpu_flags): Likewise.
	* i386-opc.tbl: Add umonitor, umwait, tpause.
	* i386-init.h: Regenerate.
	* i386-tbl.h: Likewise.