x86: Remove restriction on NOTRACK prefix position

x86: Remove restriction on NOTRACK prefix position

Since the NOTRACK prefix is no longer required to be the last prefix
before the REX prefix, restriction on the NOTRACK prefix position is
removed from assembler as well as disassembler.  Assembler encodes the
NOTRACK prefix the same way as the DS segment register, which places
it before other prefixes.  Disassembler displays prefixes in the order
they appear.

gas/

	* config/tc-i386.c (NOTRACK_PREFIX): Removed.
	(REX_PREFIX): Updated.
	(MAX_PREFIXES): Likewise.
	(parse_insn): Remove restriction on NOTRACK prefix position.
	* testsuite/gas/i386/notrack.s: Add tests with NOTRACK prefix
	before other prefixes.
	* testsuite/gas/i386/x86-64-notrack.s: Likewise.
	* testsuite/gas/i386/notrackbad.s: Remove tests with NOTRACK
	prefix before other prefixes.
	* testsuite/gas/i386/x86-64-notrackbad.s: Likewise.
	* testsuite/gas/i386/notrack-intel.d: Updated.
	* testsuite/gas/i386/notrack.d: Likewise.
	* testsuite/gas/i386/notrackbad.l: Likewise.
	* testsuite/gas/i386/x86-64-notrack-intel.d: Likewise.
	* testsuite/gas/i386/x86-64-notrack.d: Likewise.
	* testsuite/gas/i386/x86-64-notrackbad.l: Likewise.

opcodes/

	* i386-dis.c (last_active_prefix): Removed.
	(ckprefix): Don't set last_active_prefix.
	(NOTRACK_Fixup): Don't check last_active_prefix.