[ARM] Enable CRC by default for ARMv8.1 and later.

[Nick Clifton]

Hi Matthew,

> opcode/include
> 2015-12-07  Matthew Wahab  <matthew.wahab@arm.com>
>
>      * arm.h (ARM_ARCH_V8_1A): Add the CRC_EXT_ARMV8 co-processor
>      feature macro.
>      (ARM_ARCH_V8_2A): Likewise.

Approved - please apply.

Cheers
   Nick