aarch64: Add support for Armv8-R system registers

aarch64: Add support for Armv8-R system registers

This patch adds support for the system registers introduced in Armv8-R
AArch64.

gas/ChangeLog:

2020-09-08  Alex Coplan  <alex.coplan@arm.com>

	* config/tc-aarch64.c (parse_sys_reg): Also pass sysreg name to
	validation function.
	(parse_sys_ins_reg): Likewise.
	(print_operands): Pass CPU features to aarch64_print_operand().
	* testsuite/gas/aarch64/v8-r-bad-sysregs.d: New test.
	* testsuite/gas/aarch64/v8-r-bad-sysregs.l: Error output.
	* testsuite/gas/aarch64/v8-r-bad-sysregs.s: Input.
	* testsuite/gas/aarch64/v8-r-sysregs-need-arch.d: New test.
	* testsuite/gas/aarch64/v8-r-sysregs-need-arch.l: Error output.
	* testsuite/gas/aarch64/v8-r-sysregs.d: New test.
	* testsuite/gas/aarch64/v8-r-sysregs.s: Input for previous two tests.

include/ChangeLog:

2020-09-08  Alex Coplan  <alex.coplan@arm.com>

	* opcode/aarch64.h (aarch64_sys_ins_reg_supported_p): Also take
	system register name in order to simplify validation for v8-R.
	(aarch64_print_operand): Also take CPU feature set, as disassembly for
	system registers now depends on arch variant.

opcodes/ChangeLog:

2020-09-08  Alex Coplan  <alex.coplan@arm.com>

	* aarch64-dis.c (print_operands): Pass CPU features to
	aarch64_print_operand().
	* aarch64-opc.c (aarch64_print_operand): Use CPU features to determine
	preferred disassembly of system registers.
	(SR_RNG): Refactor to use new SR_FEAT2 macro.
	(SR_FEAT2): New.
	(SR_V8_1_A): New.
	(SR_V8_4_A): New.
	(SR_V8_A): New.
	(SR_V8_R): New.
	(SR_EXPAND_ELx): New.
	(SR_EXPAND_EL12): New.
	(aarch64_sys_regs): Specify which registers are only on
	A-profile, add R-profile system registers.
	(ENC_BARLAR): New.
	(PRBARn_ELx): New.
	(PRLARn_ELx): New.
	(aarch64_sys_ins_reg_supported_p): Reject EL3 registers for
	Armv8-R AArch64.