[AArch64] PR ld/21532, Allow COPY relocation elimination

[Nick Clifton]

Hi Jiong,

>    As discussed at the PR, this patch tries to avoid COPY relocation generation
> and propagate the original relocation into runtime if it was relocating on
> writable section.  The ELIMINATE_COPY_RELOCS has been set to true and it's
> underlying infrastructure has been improved so that the COPY reloc elimination
> at least working on absoluate relocations (ABS64) on AArch64 and testcases on
> the PR has passed.

Hmm - I am wondering if ELIMINATE_COPY_RELOCS should always be set, for targets
that use it.  In fact maybe we can just eliminate the macro altogether...

>    There are several other relocation types might need similar supports as well,
> I will try to post following up patches to clean up them.
> 
>    no regression on cross and native ld check.
> 
>    OK for trunk?

Approved - please apply.

Cheers
  Nick