MIPS: Fix XPA base and Virtualization ASE instruction handling

MIPS: Fix XPA base and Virtualization ASE instruction handling

Correct a commit 7d64c587c15f ("Add support for the MIPS eXtended
Physical Address (XPA) ASE.") bug, causing XPA base and Virtualization
ASE instructions to be wrongly always enabled with the selection of the
MIPS32r2 or higher ISA.

For example this source assembles successfully as shown below:

$ cat xpa.s
	mfhc0	$2, $1
$ as -32 -mips32 -o xpa.o xpa.s
xpa.s: Assembler messages:
xpa.s:1: Error: opcode not supported on this processor: mips32 (mips32) `mfhc0 $2,$1'
$ as -32 -mips32r2 -o xpa.o xpa.s
$ objdump -d xpa.o

xpa.o:     file format elf32-tradbigmips

Disassembly of section .text:

00000000 <.text>:
   0:	40420800 	mfhc0	v0,c0_random
	...
$

To address this issue remove the I33 (INSN_ISA32R2) marking from all XPA
instructions in the opcode table.  Additionally, for XPA Virtualization
ASE instructions implement an XPAVZ (ASE_XPA_VIRT) combination ASE flag
and use it in place of IVIRT|XPA (ASE_VIRT|ASE_XPA).

Now the same source is correctly rejected unless the `-mxpa' option is
also used:

$ as -32 -mips32r2 -o xpa.o xpa.s
xpa.s: Assembler messages:
xpa.s:1: Error: opcode not supported on this processor: mips32r2 (mips32r2) `mfhc0 $2,$1'
$ as -32 -mips32r2 -mxpa -o xpa.o xpa.s
$

Add test cases for XPA base and XPA Virtualization ASE instructions.

Parts of this change by Andrew Bennett.

	include/
	* opcode/mips.h (ASE_XPA_VIRT): New macro.

	opcodes/
	* mips-dis.c (mips_calculate_combination_ases): Handle the
	ASE_XPA_VIRT flag.
	(parse_mips_ase_option): New function.
	(parse_mips_dis_option): Factor out ASE option handling to the
	new function.  Call `mips_calculate_combination_ases'.
	* mips-opc.c (XPAVZ): New macro.
	(mips_builtin_opcodes): Correct ISA and ASE flags for "mfhc0",
	"mfhgc0", "mthc0" and "mthgc0".

	gas/
	* config/tc-mips.c (mips_set_ase): Handle the ASE_XPA_VIRT flag.
	* testsuite/gas/mips/xpa.d: Remove `xpa' from `-M' in `objdump'
	flags.  Add `-mvirt' to `as' flags.
	* testsuite/gas/mips/xpa-err.d: New test.
	* testsuite/gas/mips/xpa-virt-err.d: New test.
	* testsuite/gas/mips/xpa-err.l: New stderr output.
	* testsuite/gas/mips/xpa-virt-err.l: New stderr output.
	* testsuite/gas/mips/xpa-err.s: New test source.
	* testsuite/gas/mips/xpa-virt-err.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	binutils/
	* testsuite/binutils-all/mips/mips-xpa-virt-1.d: New test.
	* testsuite/binutils-all/mips/mips-xpa-virt-2.d: New test.
	* testsuite/binutils-all/mips/mips-xpa-virt-3.d: New test.
	* testsuite/binutils-all/mips/mips-xpa-virt-4.d: New test.
	* testsuite/binutils-all/mips/mips-xpa-virt.s: New test source.
	* testsuite/binutils-all/mips/mips.exp: Run the new tests.