gen-tarball: Add support for gpgmepp and gpgmeqt/qgpgme

gpgmepp and qgpgme can be packaged similar to the gpg packages that use
autotools except that we need to use cmake instead of autogen.sh and
configure. For qgpgme we need to special-case the repo because it's
called gpgmeqt.

(cherry picked from commit dc721da1157e49f5d2a2e88c9d2e0ee861e2fc70)

• GnuPG-bug-id: T7262