fewer jobs for GCC, bump to 4.9
fewer jobs for GCC, bump to 4.9

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