Pre-computes the max stack size outgoing arguments, and pre-allocates it during prolog, deallocating during epilog. With this CL, there are no more StackAdjustments needed for the ARM32, which will simplify rematerializing alloca'd variables. BUG= https://code.google.com/p/nativeclient/issues/detail?id=4076 R=sehr@chromium.org Review URL: https://codereview.chromium.org/1467473003 .
