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

[Jiong Wang]

On 07/06/17 16:17, Jiong Wang wrote:

>   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.
>    There are several other relocation types might need similar supports as well,
> I will try to post following up patches to clean up them.

Without the following up patches to cleanup some other PC-relative relocation types,  this patch
will leak PC relative relocation types in and cause incomplete support on copy relocation elimination.

This is revealed by some g++/libstdc++ test:
  
   unresolvable R_AARCH64_ADR_PREL_PG_HI21 relocation against symbol `_ZTIi@@CXXABI_1.3'

I will revert this patch temporarily and will commit it later after the work and review on PC-relative support finished.

Regards,
Jiong