Change ARM thread stack padding to 0
Change ARM thread stack padding to 0

There was never a need for any "alignment padding" or dummy return address
on an ARM thread stack.  Set the parameter to zero.

BUG=cleanup
TEST=trybots

R=jvoung@google.com

Review URL: http://codereview.chromium.org/7246014

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@5768 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

sbc100/native_client,sbc100/native_client,sbc100/native_client,sbc100/native_client,nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client,nacl-webkit/native_client,sbc100/native_client,nacl-webkit/native_client