[AArch64] Long branch veneer support far symbol defined by --defsym

[AArch64] Long branch veneer support far symbol defined by --defsym

2015-08-11  Jiong Wang  <jiong.wang@arm.com>

bfd/
  * bfd/elfnn-aarch64.c (aarch64_type_of_stub): New parameter "sym_sec".
  Loose the check for symbol from ABS section.
  (elfNN_aarch64_size_stubs): Pass sym_sec.

ld/testsuite/
  * ld-aarch64/farcall-b-defsym.s: New test.
  * ld-aarch64/farcall-bl-defsym.s: Likewise.
  * ld-aarch64/farcall-b-defsym.d: New expectation.
  * ld-aarch64/farcall-bl-defsym.d: Likewise.