[AArch64] Fix +nofp16 handling

[Nick Clifton]

Hi Szabolcs,

> gas/
> 2016-06-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	* config/tc-aarch64.c (struct aarch64_option_cpu_value_table): Add
> 	require field.
> 	(aarch64_features): Initialize require fields.
> 	(aarch64_parse_features): Handle dependencies.
> 	(aarch64_feature_enable_set, aarch64_feature_disable_set): New.
> 	(md_assemble): Use AARCH64_CPU_HAS_ALL_FEATURES.
> 	* testsuite/gas/aarch64/illegal-nofp16.s: New.
> 	* testsuite/gas/aarch64/illegal-nofp16.l: New.
> 	* testsuite/gas/aarch64/illegal-nofp16.d: New.
> 
> include/
> 2016-06-28  Szabolcs Nagy  <szabolcs.nagy@arm.com>
> 
> 	* opcode/aarch64.h (AARCH64_CPU_HAS_ALL_FEATURES): New.
> 	(AARCH64_CPU_HAS_ANY_FEATURES): New.
> 	(AARCH64_CPU_HAS_FEATURE): Define as AARCH64_CPU_HAS_ALL_FEATURES.
> 	(AARCH64_OPCODE_HAS_FEATURE): Remove.

Approved - please apply.

Cheers
  Nick