Align the ARM stack for the main thread 0mod16 at startup.  Untrusted code will not preserve 0mod16 for now. BUG= http://code.google.com/p/nativeclient/issues/detail?id=3116 TEST=run_barebones_stack_alignment16_test (hand enabled), run_exception_test Review URL: https://codereview.chromium.org/11347014
Align the ARM stack for the main thread 0mod16 at startup.  Untrusted code will
not preserve 0mod16 for now.
BUG= http://code.google.com/p/nativeclient/issues/detail?id=3116
TEST=run_barebones_stack_alignment16_test (hand enabled), run_exception_test
Review URL: https://codereview.chromium.org/11347014

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@10120 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

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