[PATCH][AArch64] Add support for GMID_EL1 register for +memtag

[Nick Clifton]

Hi Kyrill,

> opcodes/ChangeLog
> 2019-07-22  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
> 
> Â Â Â  * aarch64-opc.c (aarch64_sys_regs): Add gmid_el1 entry.
> Â Â Â  (aarch64_sys_reg_supported_p): Handle gmid_el1 encoding.
> 
> gas/ChangeLog
> 2019-07-22  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
> 
> Â Â Â  * testsuite/gas/aarch64/sysreg-4.s: Test gmid_el1 read.
> Â Â Â  * testsuite/gas/aarch64/sysreg-4.d: Update expected output.
> Â Â Â  * testsuite/gas/aarch64/illegal-sysreg-4.l: Likewise.

Approved - please apply.

Cheers
  Nick