[Patch][Gold] BE8 for ARM

[Cary Coutant]

> Please find attached the BE8 patch that includes support for thumb as well.
> I tested it on a hello world and bzip2 example for both arm and thumb besides a large arm application (size ~120MB).
> No regressions with the gold test-suite for arm.
>
> gold/ChangeLog
> 2016-08-15  Bharathi Seshadri  <bseshadr@cisco.com>
>
>         * options.h (General_options): Add --be8 option.
>         * arm.cc (Arm_relobj::do_relocate_sections): Add code to swap for be8.
>           (Output_data_plt_arm_standard::do_fill_first_plt_entry): Likewise.
>           (Output_data_plt_arm_short::do_fill_plt_entry): Likewise.
>           (Output_data_plt_arm_long::do_fill_plt_entry): Likewise.
>           (Target_arm::do_adjust_elf_header): Do EF_ARM_BE8 adjustment.

Committed. Thanks!

-cary