improve the release script
improve the release script

 * Build more parts
 * Build them faster
 * Use make distcheck correctly, only once at the end, not requiring
   a special configuration

Signed-off-by: Martin Kepplinger <5f224f582e4d41e2bdb8535d23e6b63d7ab1203d@ginzinger.com>

kergoth/tslib,kergoth/tslib,kergoth/tslib,kergoth/tslib