MIPS16: Handle non-extensible instructions correctly

MIPS16: Handle non-extensible instructions correctly

Identify non-extensible instructions in the MIPS16 opcode table and
disallow their use with the `.e' instruction size suffix in assembly and
do not interpret any EXTEND prefix present as a part of the instruction
in disassembly.

According to all versions of the MIPS16 ASE specifications the following
instructions encodings are not extensible [1][2][3][4][5][6]: I8/MOV32R,
I8/MOVR32, all RRR minor opcodes, all RR minor opcodes except from DSRA
and DSRL, and EXTEND itself, and as from revision 2.50 of the MIPS16e
ASE specifications it has been further clarified what was previously
implied, that non-extesiable instructions when preceded with an EXTEND
prefix must cause a Reserved Instruction exception [3][5].

Therefore in the presence of an EXTEND prefix none of these instructions
are supposed to be handled as extended instructions and supporting these
forms in disassembly causes confusion, and in the case of the RRR major
opcode it also clashes with the ASMACRO encoding.

References:

[1] "Product Description, MIPS16 Application-Specific Extension",
    Version 1.3, MIPS Technologies, Inc., 970130, Table 3. "MIPS16
    Instruction Set Summary", p. 5

[2] same, Table 5 "RR Minor Opcodes (RR-type instructions)", p.10

[3] "MIPS32 Architecture for Programmers, Volume IV-a: The MIPS16e
    Application-Specific Extension to the MIPS32 Architecture", MIPS
    Technologies, Inc., Document Number: MD00076, Revision 2.63, July
    16, 2013, Section 3.9 "MIPS16e Instruction Summaries", pp. 37-39

[4] same, Section 3.15 "Instruction Bit Encoding", pp. 46-49

[5] "MIPS64 Architecture for Programmers, Volume IV-a: The MIPS16e
    Application-Specific Extension to the MIPS64 Architecture", MIPS
    Technologies, Inc., Document Number: MD00077, Revision 2.60, June
    25, 2008, Section 1.9 "MIPS16e Instruction Summaries", pp. 38-41

[6] same, Section 1.15 "Instruction Bit Encoding", pp. 48-51

	include/
	* opcode/mips.h (INSN2_SHORT_ONLY): New macro.

	gas/
	* config/tc-mips.c (is_size_valid_16): Disallow a `.e' suffix
	instruction size override for INSN2_SHORT_ONLY opcode table
	entries.
	* testsuite/gas/mips/mips16-extend-swap.d: Adjust output.
	* testsuite/gas/mips/mips16-macro-e.l: Adjust error messages.
	* testsuite/gas/mips/mips16-32@mips16-macro-e.l: Adjust error
	messages.
	* testsuite/gas/mips/mips16e-32@mips16-macro-e.l: Adjust error
	messages.
	* testsuite/gas/mips/mips16-insn-e.d: New test.
	* testsuite/gas/mips/mips16-insn-t.d: New test.
	* testsuite/gas/mips/mips16-32@mips16-insn-e.d: New test.
	* testsuite/gas/mips/mips16-64@mips16-insn-e.d: New test.
	* testsuite/gas/mips/mips16e-32@mips16-insn-e.d: New test.
	* testsuite/gas/mips/mips16-32@mips16-insn-t.d: New test.
	* testsuite/gas/mips/mips16-64@mips16-insn-t.d: New test.
	* testsuite/gas/mips/mips16e-32@mips16-insn-t.d: New test.
	* testsuite/gas/mips/mips16-insn-e.l: New stderr output.
	* testsuite/gas/mips/mips16-insn-t.l: New stderr output.
	* testsuite/gas/mips/mips16-32@mips16-insn-e.l: New stderr
	output.
	* testsuite/gas/mips/mips16-64@mips16-insn-e.l: New stderr
	output.
	* testsuite/gas/mips/mips16e-32@mips16-insn-e.l: New stderr
	output.
	* testsuite/gas/mips/mips16-32@mips16-insn-t.l: New stderr
	output.
	* testsuite/gas/mips/mips16-64@mips16-insn-t.l: New stderr
	output.
	* testsuite/gas/mips/mips16e-32@mips16-insn-t.l: New stderr
	output.
	* testsuite/gas/mips/mips16-insn-e.s: New test source.
	* testsuite/gas/mips/mips16-insn-t.s: New test source.
	* testsuite/gas/mips/mips.exp: Run the new tests.

	opcodes/
	* mips-dis.c (print_insn_mips16): Disallow EXTEND prefix
	matching for INSN2_SHORT_ONLY opcode table entries.
	* mips16-opc.c (SH): New macro.
	(mips16_opcodes): Set SH in `pinfo2' for non-extensible
	instruction entries: "nop", "addu", "and", "break", "cmp",
	"daddu", "ddiv", "ddivu", "div", "divu", "dmult", "dmultu",
	"drem", "dremu", "dsllv", "dsll", "dsrav", "dsra", "dsrlv",
	"dsrl", "dsubu", "exit", "entry", "jalr", "jal", "jr", "j",
	"jalrc", "jrc", "mfhi", "mflo", "move", "mult", "multu", "neg",
	"not", "or", "rem", "remu", "sllv", "sll", "slt", "sltu",
	"srav", "sra", "srlv", "srl", "subu", "xor", "sdbbp", "seb",
	"seh", "sew", "zeb", "zeh", "zew" and "extend".

	binutils/
	* testsuite/binutils-all/mips/mips16-extend-insn.d: New test.
	* testsuite/binutils-all/mips/mips16-extend-insn.s: New test
	source.
	* testsuite/binutils-all/mips/mips.exp: Run the new tests.