[ARM] Add feature check for ARMv8.1 AdvSIMD instructions.

[ARM] Add feature check for ARMv8.1 AdvSIMD instructions.

gas/
2016-03-04  Matthew Wahab  <matthew.wahab@arm.com>

	* config/gas/tc-arm.c (fpu_neon_ext_v8_1): Restrict to the ARMv8.1 RDMA
	feature.
	(record_feature_use): New.
	(mark_feature_used): Use record_feature_use.
	(do_neon_qrdmlah): New.
	(insns): Use do_neon_qrdmlah for vqrdmlah and vqrdmlsh and
	variants.
	(arm_extensions): Put into alphabetical order.  Re-indent "simd"
	and "rdma" entries.  Fix the incorrect merge value for "+rdma".
	* testsuite/gas/arm/armv8-a+rdma-warning.d: New.
	* testsuite/gas/arm/armv8-a+rdma.d: Add assembler command line options.
	Make source file explicit.
	* testsuite/gas/arm/armv8-a+rdma.l: New.
	* testsuite/gas/arm/armv8-a+rdma.s: Remove .arch and .arch_extension
	directives.  Fix white-space.
	* testsuite/gas/arm/armv8_1-a+simd.d: New.

include/opcode
2016-03-04  Matthew Wahab  <matthew.wahab@arm.com>

	* arm.h (ARM_ARCH_V8_1A): Add FPU_NEON_EXT_RDMA.
	(ARM_CPU_HAS_FEATURE): Add comment.

Change-Id: Ie19250e8fa50aed44e44ab40ff30b04b38bc1a3d