Subzero. Eliminates the use of Variable64On32 as operands in ARM.

This is in preparation for adding atomic support to the ARM backend.
Moreover, the code is becoming increasingly complicated due to the use
of Variable64On32 as instruction operands.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4076
R=kschimpf@google.com

Review URL: https://codereview.chromium.org/1372083002 .
5 files changed