fix perldir to at least point to install the same place as the code looks for it.  Note, on fhs type builds, where prefix is /usr, these files are going to go into /usr/perl, which probably isn't right, but thats where the code looks too, we should do something better for builds that are not in the prefix
Drop mod_perl from the debian build temporarily

We'll add this back when the build issues with it get worked out.
See FS-6385.