New package: xbindkeys-config

The patch is borrowed verbatim from Debian. It is under the same
license as the rest of the package, and is necessary for the app to
work.

There does not seem to be a canonical upstream homepage for this app
other than Debian itself.

Change-Id: I4f0bec32a95778fb12a48bfb280386b65a0d0f9a