Comment 3 for bug 656285

Pardon, badly phrased on my part- basically we can get either -1 or old. If we changed that conditional w/in arm-semi.c to:

if (-1 != limit && limit != ts->heap_base) {

that should do the trick in a cross platform way, although we'll have to tweak the for loop to handle when limit degrades to 0. Note that this isn't the only spot that has the -1 assumption- m68-semi.c is the same. Also, linux-user/m68k-sim.c looks a bit odd in light of this discussion (that one I don't quite get- it checks for -ENOMEM which is supposed to be an alpha only return).