Add missing LIBPROTOBUF_EXPORT

src/google/protobuf/util/json_util.h

diff --git a/src/google/protobuf/util/json_util.h b/src/google/protobuf/util/json_util.h
index 170ae91..6d3cee5 100644
--- a/src/google/protobuf/util/json_util.h
+++ b/src/google/protobuf/util/json_util.h
@@ -73,7 +73,7 @@
 // Converts from protobuf message to JSON. This is a simple wrapper of
 // BinaryToJsonString(). It will use the DescriptorPool of the passed-in
 // message to resolve Any types.
-util::Status MessageToJsonString(const Message& message,
+LIBPROTOBUF_EXPORT util::Status MessageToJsonString(const Message& message,
                                    string* output,
                                    const JsonOptions& options);
 
@@ -85,7 +85,7 @@
 // Converts from JSON to protobuf message. This is a simple wrapper of
 // JsonStringToBinary(). It will use the DescriptorPool of the passed-in
 // message to resolve Any types.
-util::Status JsonStringToMessage(const string& input,
+LIBPROTOBUF_EXPORT util::Status JsonStringToMessage(const string& input,
                                    Message* message,
                                    const JsonParseOptions& options);
 
@@ -100,7 +100,7 @@
 //   2. input is not valid protobuf wire format, or conflicts with the type
 //      information returned by TypeResolver.
 // Note that unknown fields will be discarded silently.
-util::Status BinaryToJsonStream(
+LIBPROTOBUF_EXPORT util::Status BinaryToJsonStream(
     TypeResolver* resolver,
     const string& type_url,
     io::ZeroCopyInputStream* binary_input,
@@ -135,7 +135,7 @@
 //   1. TypeResolver fails to resolve a type.
 //   2. input is not valid JSON format, or conflicts with the type
 //      information returned by TypeResolver.
-util::Status JsonToBinaryStream(
+LIBPROTOBUF_EXPORT util::Status JsonToBinaryStream(
     TypeResolver* resolver,
     const string& type_url,
     io::ZeroCopyInputStream* json_input,