perl: improved perl.conf to set vendorprefix and removed superfluous whitespace.

We lost the ability to set vendorprefix at 23f83f9dc35c4ece3fd710c18cfd5a63babdf3fc,
we need it because http://git.opensde.net/opensde/opensde-nopast/commit/?id=aabb0ba8327333231997f77910673fefda46935c