fix compiler warning (warning: field 'expected_query_bbox_' will be initialized after base 'mapnik::memory_datasource' [-Wreorder])
fix compiler warning (warning: field 'expected_query_bbox_' will be initialized after base 'mapnik::memory_datasource' [-Wreorder])

mapnik/mapnik,mapnik/mapnik,lightmare/mapnik,naturalatlas/mapnik,tomhughes/mapnik,tomhughes/mapnik,mapnik/mapnik,tomhughes/mapnik,lightmare/mapnik,naturalatlas/mapnik,naturalatlas/mapnik,lightmare/mapnik,tomhughes/mapnik,mapnik/mapnik,naturalatlas/mapnik,lightmare/mapnik