dnn: both protobuf readers have similar behavior

- ReadProtoFromTextFile
- ReadProtoFromTextBuffer

modules/dnn/src/caffe/caffe_io.cpp

@@ -1137,7 +1137,12 @@ bool ReadProtoFromBinaryFile(const char* filename, Message* proto) {
 
 bool ReadProtoFromTextBuffer(const char* data, size_t len, Message* proto) {
     ArrayInputStream input(data, len);
-    return google::protobuf::TextFormat::Parse(&input, proto);
+#ifndef OPENCV_DNN_EXTERNAL_PROTOBUF
+    return google::protobuf::TextFormat::Parser(true).Parse(&input, proto);
+#else
+    return google::protobuf::TextFormat::Parser().Parse(&input, proto);
+#endif
+
 }