Support creating tarballs for more packages specified by name

* packages/gen-tarball.sh: Support some GnuPG projects by name. Assume
package by KDE if name starts with 'k' or 'libk'.

This makes it possible to create tarballs for the most important (for
gpg4win) GnuPG projects and for many KDE projects (in particular,
kleopatra and libkleo).