Nonmoving GC may drop update remembered set blocks due to `setNumCapabilities`

Storage.c:storageAddCapabilities currently has the following:

    // Initialize NonmovingAllocators and UpdRemSets
    if (RtsFlags.GcFlags.useNonmoving) {
        nonmovingAddCapabilities(to);
        for (i = 0; i < to; ++i) {
            nonmovingInitUpdRemSet(&getCapability(i)->upd_rem_set);
        }
    }

This is subtly wrong: the lower iteration bound of 0 means we end up re-initializing (and therefore clearing) the update-remembered sets of capabilities which already exist. This lower bound rather should be from.

This can result in undefined behavior in programs using the nonmoving GC and setNumCapabilities.