On the previous version of the package, the there was a dirs file with
"usr/share/gerwin". But after the package was created, this path stayed empty.

The software was renamed from GerWin to Ferret, so the dirs file is not
necessary.

From http://www.nongnu.org/gerwin/project/what.html the software
The GerWin project has changed its name!
The GerWin project has changed its name to GNU Ferret: GNU Free Entity
Relationship and Reverse Engineering Tool. The rationale behind the name
changing is to avoid future legal conflicts with the owners of the
Erwin(TM) trademark.

 -- Paulo Henrique de Lima Santana (phls) <phls@softwarelivre.org>  Wed, 09 Nov 2016 23:43:14 -0200
