fix path to png
fix path to png

springmeyer/mapnik-c-api,fawick/mapnik-c-api,springmeyer/mapnik-c-api,fawick/mapnik-c-api,fawick/mapnik-c-api,springmeyer/mapnik-c-api,fawick/mapnik-c-api,fawick/mapnik-c-api,springmeyer/mapnik-c-api,springmeyer/mapnik-c-api