debug symbols for package cowbuilder

 'cowbuilder' command is a wrapper for pbuilder which allows using
 pbuilder-like interface over cowdancer environment.
 .
 pbuilder is a tool for building and testing Debian package inside a clean
 chroot, and cowbuilder allows chroot to be recreated using
 hard-linked copies with copy-on-write, which makes creation and
 destruction of chroots fast.