rc.shutdown : Swapoff reworked
Former Puppies had used busybox swapoff that
a) unfortunately does not recognize nor ignore the -v verbose option
b) works only if swaps are in /etc/fstab or /etc/mtab

Newer Puppies use swapoff from the util-linux package, which recently became
a symlink to swapon, which reads
In case /proc/swaps exists, unswap stuff listed there.

Added "uneccessary" feature to give a warning if not which swapoff .