update pbf.hpp
update pbf.hpp

mapbox/mapnik-vector-tile,tomhughes/mapnik-vector-tile,mapbox/mapnik-vector-tile,tomhughes/mapnik-vector-tile,landsurveyorsunited/mapnik-vector-tile,mapbox/mapnik-vector-tile,landsurveyorsunited/mapnik-vector-tile,landsurveyorsunited/mapnik-vector-tile,tomhughes/mapnik-vector-tile,tomhughes/mapnik-vector-tile,mapbox/mapnik-vector-tile