Remove the last vestiges of the MAKE_PTR/MAKE_OFFSET mechanism. We haven't

Remove the last vestiges of the MAKE_PTR/MAKE_OFFSET mechanism.  We haven't
allowed different processes to have different addresses for the shmem segment
in quite a long time, but there were still a few places left that used the
old coding convention.  Clean them up to reduce confusion and improve the
compiler's ability to detect pointer type mismatches.

Kris Jurka