Log Message:
Upgrading Xfce to 4.6.1.

This is for PR #40984. This is based on work from
dieter roelants. Thank you Dieter.
Also I had done some work independently on this.
Hopefully, I am getting this all committed at one time.

The changelogs are at
http://www.xfce.org/documentation/changelogs/4.6.1
http://www.xfce.org/documentation/changelogs/4.6.0

Also don't need the xfce4-dev-tools for building. (It is only
needed when building from SVN source.)