ifnet: Remove marker from if_multiaddrs, once iteration is done

Reported-by: tuxillo@
groff - horrible hack to fix .gz issues

* If a gzipped manual page contains a .so forwarding entry, groff
  will attempt to open the forwarding entry directly and will not
  check to see if a file with a .gz extension is present, resulting
  in an open error.

* Hack hack hack.  Horrible hack of the input search path to check
  for a .gz extension and popen() the file with zcat.  Horrible because
  I haven't bothered to modify all the other myrid code to properly call
  pclose() instead of fclose() in that case.
kernel: Remove some unused code.
loader: Remove some unused code.