The last argument in mk_metaball(..) defined in src/libwdb/wdb.c looks erroneous to me
it reads fastf_t *verts
As per  this means verts is a 5 array of pointers of type floats.
Instead i think this should be fastf_t (*verts) which would mean verts is a pointer to 5 array of fastf_t.
Please see if my explanations is right!