Add MIPS32 DSPr3 support.

Add MIPS32 DSPr3 support.

bfd/

	* elfxx-mips.c (print_mips_ases): Add DSPR3.

binutils/

	* readelf.c (print_mips_ases): Add DSPR3.

gas/

	* config/tc-mips.c (options): Add OPTION_DSPR3 and
	OPTION_NO_DSPR3.
	(md_longopts): Likewise.
	(md_show_usage): Add help for -mdspr3 and -mno-dspr3.
	(mips_ases): Define availability for DSPr3.
	(mips_ase_groups): Add ASE_DSPR3 to the DSP group.
	(mips_convert_ase_flags): Map ASE_DSPR3 to AFL_ASE_DSPR3.
	* doc/as.texinfo: Document -mdspr3, -mno-dspr3.  Fix -mdspr2
	formatting.
	* doc/c-mips.texi: Document -mdspr3, -mno-dspr3, .set dspr3 and
	.set nodspr3.  Fix -mdspr2 formatting.
	* testsuite/gas/mips/mips32-dspr3.d: New file.
	* testsuite/gas/mips/mips32-dspr3.s: Likewise.
	* testsuite/gas/mips/mips.exp: Run mips32-dspr3 test.

include/

	* elf/mips.h (AFL_ASE_DSPR3): New macro.
	(AFL_ASE_MASK): Update to include AFL_ASE_DSPR3.
	* opcode/mips.h (ASE_DSPR3): New macro.

opcodes/

	* mips-dis.c (mips_arch_choices): Add ASE_DSPR3 to mips32r6 and
	mips64r6.
	* mips-opc.c (D34): New macro.
	(mips_builtin_opcodes): Define bposge32c for DSPr3.