Add ARROW_FLIGHT_EXPORT for Windows symbol visibility

Author: raulcd

cpp/src/arrow/flight/serialization_internal.h

@@ -187,6 +187,7 @@ ARROW_FLIGHT_EXPORT
 arrow::Result<arrow::BufferVector> SerializePayloadToBuffers(const FlightPayload& msg);
 
 /// \brief Deserialize FlightData from a contiguous buffer.
+ARROW_FLIGHT_EXPORT
 arrow::Result<internal::FlightData> DeserializeFlightData(
     const std::shared_ptr<arrow::Buffer>& buffer);
 

cpp/src/arrow/flight/transport.h

@@ -76,7 +76,7 @@ class FlightStatusDetail;
 namespace internal {
 
 /// Internal, not user-visible type used for memory-efficient reads
-struct FlightData {
+struct ARROW_FLIGHT_EXPORT FlightData {
   /// Used only for puts, may be null
   std::unique_ptr<FlightDescriptor> descriptor;