Bug#946613: Consider making gtk3.22-client the one installed by 'freeciv' package

[Marko Lindqvist]

Package: freeciv
Version:   2.6.0-4

Freeciv doc/README.packaging about the new gtk3.22-client:
"This client suits better for systems with gtk+-3.22 than the
gtk3-client compatible with much older gtk+ versions."

 (Since that text has been written, gtk+ project changed their
decision that 3.22 would be the last version of gtk+-3. Above should
say that "...systems with gtk+-3.22 or gtk+-3.24...")

 - ML