MIPS: Add Global INValidate ASE support

MIPS: Add Global INValidate ASE support

Add support for the Global INValidate Application Specific Extension
for Release 6 of the MIPS Architecture.

[1] "MIPS Architecture for Programmers Volume II-A: The MIPS32
    Instruction Set Manual", Imagination Technologies Ltd., Document
    Number: MD00086, Revision 6.06, December 15, 2016, Section 3.2
    "Alphabetical List of Instructions", pp. 187-191

bfd/
	* elfxx-mips.c (print_mips_ases): Add GINV extension.

binutils/
	* readelf.c (print_mips_ases): Add GINV extension.

gas/
	* NEWS: Mention MIPS Global INValidate ASE support.
	* config/tc-mips.c (options): Add OPTION_GINV and OPTION_NO_GINV.
	(md_longopts): Likewise.
	(mips_ases): Define availability for GINV.
	(mips_convert_ase_flags): Map ASE_GINV to AFL_ASE_GINV.
	(md_show_usage): Add help for -mginv and -mno-ginv.
	* doc/as.texinfo: Document -mginv, -mno-ginv.
	* doc/c-mips.texi: Document -mginv, -mno-ginv, .set ginv and
	.set noginv.
	* testsuite/gas/mips/ase-errors-1.s: Add error checks for GINV
	ASE.
	* testsuite/gas/mips/ase-errors-2.s: Likewise.
	* testsuite/gas/mips/ase-errors-1.l: Likewise.
	* testsuite/gas/mips/ase-errors-2.l: Likewise.
	* testsuite/gas/mips/ginv.d: New test.
	* testsuite/gas/mips/ginv-err.d: New test.
	* testsuite/gas/mips/ginv-err.l: New test stderr output.
	* testsuite/gas/mips/ginv.s: New test source.
	* testsuite/gas/mips/ginv-err.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.

include/
	* elf/mips.h (AFL_ASE_GINV, AFL_ASE_RESERVED1): New macros.
	(AFL_ASE_MASK): Update to include AFL_ASE_GINV.
	* opcode/mips.h: Document "+\" operand format.
	(ASE_GINV): New macro.

opcodes/
	* mips-dis.c (mips_arch_choices): Add GINV to mips32r6 and
	mips64r6 descriptors.
	(parse_mips_ase_option): Handle -Mginv option.
	(print_mips_disassembler_options): Document -Mginv.
	* mips-opc.c (decode_mips_operand) <+\>: New operand format.
	(GINV): New macro.
	(mips_opcodes): Define ginvi and ginvt.