am 21ec779a: Add stack unwinding directives to atomic-android-arm.S.

Merge commit '21ec779abe2df0c2e9e170a40c8cf7c2f2eb4ac9' into eclair-mr2

* commit '21ec779abe2df0c2e9e170a40c8cf7c2f2eb4ac9':
  Add stack unwinding directives to atomic-android-arm.S.