Fix rivlib test's cmakelists
Fix rivlib test's cmakelists

The plugin directory was named incorrectly, breaking tests.

lucadelu/PDAL,boundlessgeo/PDAL,lucadelu/PDAL,boundlessgeo/PDAL,mtCarto/PDAL,boundlessgeo/PDAL,radiantbluetechnologies/PDAL,Sciumo/PDAL,DougFirErickson/PDAL,mtCarto/PDAL,mtCarto/PDAL,jwomeara/PDAL,mtCarto/PDAL,radiantbluetechnologies/PDAL,Sciumo/PDAL,jwomeara/PDAL,lucadelu/PDAL,DougFirErickson/PDAL,jwomeara/PDAL,lucadelu/PDAL,radiantbluetechnologies/PDAL,DougFirErickson/PDAL,mpgerlek/PDAL-old,radiantbluetechnologies/PDAL,boundlessgeo/PDAL,mpgerlek/PDAL-old,mpgerlek/PDAL-old,mpgerlek/PDAL-old,DougFirErickson/PDAL,Sciumo/PDAL,jwomeara/PDAL,Sciumo/PDAL