[Xymon] Minor bug found in xymonclient-linux.sh

I have been frustrated by the inclusion of tmpfs filesystems in xymon's client-side disk test. So I decided to see if I could fix the problem.

Running version 4.3.30.

In xymonclient-linux.sh, when defining the list of filesystem types to exclude, one of the commands it pipes through is this:

egrep -v 'tmpfs|rootfs|squashfs'

This grep removes tmpfs from the list of filesystems to exclude. So tmpfs filesystems are included. Changing the command to the following fixes the immediate problem that I have, but it should be reviewed for sanity by someone who's much more familiar with the code:

egrep -v 'rootfs|squashfs'

I actually came up with a command to define the excludes that's a little bit cleaner, but it required changes to more than just the one piped command. Let me know if you're interested in that.

Thanks, Shawn