plugin update: check_mem.pl

From: Dan Larsson <dl@tyfon.net>
Date: Sun, 16 Jul 2000 19:50:32 +0200 (CEST)

Version 1.2:
* Include swap space switch added
* Misc bug fixes

Note:
* The plugin is created and only tested on
FreeBSD v3.x/4.0

Download:
* http://tyfon.net/download/check_mem.pl