Don't put a trailing dot in set_package_properties

It looks weird given the kind of visualization where this text is
displayed.

Bad:

 * XKB (required version >= 0.5.0), XKB API common to servers and clients., <http://xkbcommon.org>

Good:

 * XKB (required version >= 0.5.0), XKB API common to servers and clients, <http://xkbcommon.org>