Enable gencat for i386_fbsd_*

Enable gencat for i386_fbsd_*

The machines certainly have a /usr/bin/gencat, and I see nothing
in history to indicate a reason for this prevention.
Allow the 32-bit machines to build afszcm.cat and make packaging
more uniform between architectures.

Change-Id: If1017d28cc804d58cfb29019158ad5b3d70da9ac
Reviewed-on: http://gerrit.openafs.org/4760
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>