Subzero. Removes X8664_STACK_HACK from the crosstests.

X8664_STACK_HACK was an intrusive way to get the crosstests to run
while x32 support was not implemented in llvm. The hack is longer
needed.

R=eholk@chromium.org

Review URL: https://codereview.chromium.org/1706883003 .
16 files changed