[project @ 1998-03-11 14:26:23 by simonm]

- move SIZEOF checks together (previous commit added SIZEOF checks to
   a different part of the file).

 - check alignment of longs:  unsigned ints are no good, because we need to
   check whether f.e. a float can be put on the stack, which is
   StgWord aligned, and currently an StgWord is basically a long.