[PATCH][AArch64] Add ARMv8.3 command line option and feature flag

[Nick Clifton]

Hi Szabolcs,

> gas/
> 2016-11-07  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	* config/tc-aarch64.c (aarch64_archs): Add "armv8.3-a".
> 	* doc/c-aarch64.texi (-march): Likewise.
> 
> include/opcode/
> 2016-11-07  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	* aarch64.h (AARCH64_FEATURE_V8_3): New.
> 	(AARCH64_ARCH_V8_3): New.
> 	(AARCH64_ARCH_V8_1, AARCH64_ARCH_V8_2): Simplify.

Approved - please apply.

Cheers
  Nick