align 32bit integers. Use explicit sized typing at some other places.
XXX This still won't fix lfs for 64bit machines, as we have some
assumptions about sizeof(pointer)=sizeof(u_int32_t) in here, and (if I
looked right) a misaligned u_int64_t. The right fix (to cite cgd) will
be to seperate on-disk-representation from in-core, but I don't have
the time (at the moment) to do this.