Convert Exiv2::ErrorCode into an enum class

samples/iptcprint.cpp

@@ -25,7 +25,7 @@ try {
     if (iptcData.empty()) {
         std::string error(argv[1]);
         error += ": No IPTC data found in the file";
-        throw Exiv2::Error(Exiv2::kerErrorMessage, error);
+        throw Exiv2::Error(Exiv2::ErrorCode::kerErrorMessage, error);
     }
 
     auto end = iptcData.end();