[AArch64][PATCH 1/2] Add support for ARMv8.2 DC CVAP instruction.

ARMv8.2 adds the new system instruction DC CVAP. This patch series adds
support for this instruction to binutils, enabled when -march=armv8.2-a
is selected.

The AArch64 binutils record of some system registers uses a boolean
value to hold the single flag currently supported for them. To allow
these registers to be limited to specific architectures, the first patch
in this series replaces the boolean flag with a bitset and feature test.

include/opcode/
2015-12-10  Matthew Wahab  <matthew.wahab@arm.com>

	* aarch64.h (aarch64_sys_ins_reg): Replace has_xt with flags.
	(aarch64_sys_ins_reg_has_xt): Declare.

opcodes/
2015-12-10  Matthew Wahab  <matthew.wahab@arm.com>

	* aarch64-dis.c (aarch64_ext_regrt_sysins): Replace use of has_xt
	with aarch64_sys_ins_reg_has_xt.
	(aarch64_ext_sysins_op): Likewise.
	* aarch64-opc.c (operand_general_constraint_met_p): Likewise.
	(F_HASXT): New.
	(aarch64_sys_regs_ic): Update for changes to aarch64_sys_ins_reg.
	(aarch64_sys_regs_dc): Likewise.
	(aarch64_sys_regs_at): Likewise.
	(aarch64_sys_regs_tlbi): Likewise.
	(aarch64_sys_ins_reg_has_xt): New.

Change-Id: I363637a6c3f54d7ffff953b3a0734e8139cae819