Restore searching in sub directories

With earlier version of fgc, one could cd into a sub directory and
use fgc to find the German comments in there.
This change restores that behaviour again.

Change-Id: I2fa30ff98af0418c7531b94f19ff0b81f76abddd
Reviewed-on: https://gerrit.libreoffice.org/11522
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>