[AArch64] Don't tail-pads sections to the alignment

[Nicholas Clifton]

Hi Jiong,

> 2015-03-09  Jiong Wang  <jiong.wang@arm.com>
>
> gas/
>    * config/tc-aarch64.h (SUB_SEGMENT_ALIGN): Define to be zero.
>
> gas/testsuite/
>    * gas/aarch64/tail_padding.s: New testcase.
>    * gas/aarch64/tail_padding.d: New expectation file.

Approved - please apply.

Cheers
   Nick