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.
- GnuPG-bug-id: T7262