ARM mapping symbols and --strip-unneeded

[Nick Clifton]

Hi Guys,

>> We should check aarch64 target as it might have the same issue too as
>> it uses $d and $t too.

> Although AArch64 ELF defines some mapping symbols, I don't think they
> are currently needed beyond being helpers for disassembly (code vs data).

I think that they might be needed for the Cortex-A53 erratum 835769...

Anyway I have now checked in a patch that duplicates the ARM mapping symbol
preservation code for the AAcrh64, although restricted to AArch64 mapping
symbols, obviously.

Cheers
  Nick