remove debug print

plugins/input/gdal/gdal_datasource.cpp

@@ -50,7 +50,6 @@ extern "C" MAPNIK_EXP void on_plugin_load()
 {
     // initialize gdal formats
     std::call_once(once_flag,[](){
-        std::clog << "calling once gdal\n";
         GDALAllRegister();
     });
 }

plugins/input/ogr/ogr_datasource.cpp

@@ -66,7 +66,6 @@ extern "C" MAPNIK_EXP void on_plugin_load()
     // initialize ogr formats
     // NOTE: in GDAL >= 2.0 this is the same as GDALAllRegister()
     std::call_once(once_flag,[](){
-        std::clog << "calling once ogr\n";
         OGRRegisterAll();
     });
 }