aarch64: Enforce P/M/E order for MOPS instructions

aarch64: Enforce P/M/E order for MOPS instructions

The MOPS instructions should be used as a triple, such as:

       cpyfp [x0]!, [x1]!, x2!
       cpyfm [x0]!, [x1]!, x2!
       cpyfe [x0]!, [x1]!, x2!

The registers should also be the same for each writeback operand.
This patch adds a warning for code that doesn't follow this rule,
along similar lines to the warning that we already emit for
invalid uses of MOVPRFX.

include/
	* opcode/aarch64.h (C_SCAN_MOPS_P, C_SCAN_MOPS_M, C_SCAN_MOPS_E)
	(C_SCAN_MOPS_PME): New macros.
	(AARCH64_OPDE_A_SHOULD_FOLLOW_B): New aarch64_operand_error_kind.
	(AARCH64_OPDE_EXPECTED_A_AFTER_B): Likewise.
	(aarch64_operand_error): Make each data value a union between
	an int and a string.

opcodes/
	* aarch64-tbl.h (MOPS_CPY_OP1_OP2_INSN): Add scan flags.
	(MOPS_SET_OP1_OP2_INSN): Likewise.
	* aarch64-opc.c (set_out_of_range_error): Update after change to
	aarch64_operand_error.
	(set_unaligned_error, set_reg_list_error): Likewise.
	(init_insn_sequence): Use a 3-instruction sequence for
	MOPS P instructions.
	(verify_mops_pme_sequence): New function.
	(verify_constraints): Call it.
	* aarch64-dis.c (print_verifier_notes): Handle
	AARCH64_OPDE_A_SHOULD_FOLLOW_B and AARCH64_OPDE_EXPECTED_A_AFTER_B.

gas/
	* config/tc-aarch64.c (operand_mismatch_kind_names): Add entries
	for AARCH64_OPDE_A_SHOULD_FOLLOW_B and AARCH64_OPDE_EXPECTED_A_AFTER_B.
	(operand_error_higher_severity_p): Check that
	AARCH64_OPDE_A_SHOULD_FOLLOW_B and AARCH64_OPDE_EXPECTED_A_AFTER_B
	come between AARCH64_OPDE_RECOVERABLE and AARCH64_OPDE_SYNTAX_ERROR;
	their relative order is not significant.
	(record_operand_error_with_data): Update after change to
	aarch64_operand_error.
	(output_operand_error_record): Likewise.  Handle
	AARCH64_OPDE_A_SHOULD_FOLLOW_B and AARCH64_OPDE_EXPECTED_A_AFTER_B.
	* testsuite/gas/aarch64/mops_invalid_2.s,
	testsuite/gas/aarch64/mops_invalid_2.d,
	testsuite/gas/aarch64/mops_invalid_2.l: New test.