if stack is in low memory and frame size is huge, test could wrap around!
fix by omitting test altogether if we know frame is big.
R=gri
OCL=14782
CL=14782
these guys really really want long to be 32-bits,
so ,s/long/int32/ (and then manual fixup).
still passes all tests.
(i started out looking for just those longs that
needed to be int32 instead, and it was just too hard
to track them down one by one.)
the longs were rare enough that i don't think
it will cause integration problems.
R=ken
OCL=13787
CL=13789
