[AArch64] Create .got section if _GLOBAL_OFFSET_TABLE_ referenced

[AArch64] Create .got section if _GLOBAL_OFFSET_TABLE_ referenced

2016-03-07  Jiong Wang  <jiong.wang@arm.com>

bfd/
  * elfnn-aarch64.c (elfNN_aarch64_check_relocs): Always create .got section
  if the symbol "_GLOBAL_OFFSET_TABLE_" referenced.

ld/
  * testsuite/ld-aarch64/implicit_got_section_1.s: New test source file.
  * testsuite/ld-aarch64/implicit_got_section_1.d: New test expected result.
  * testsuite/ld-aarch64/aarch64-elf.exp: Run new test.