Add setTimestamping in AsyncUDPServerSocket

Summary: Enabled the owner of AsyncUDPServerSocket to call setTimestamping for the underlying AsyncUDPSocket. So in the `onDataAvailable` callback we could have ts set in `OnDataAvailableParams`

Reviewed By: yfeldblum

Differential Revision: D28661584

fbshipit-source-id: d060cfdd8a4e105ada8a2c3b0fd13ddafb6f0d7c

folly/io/async/AsyncUDPServerSocket.h

@@ -246,6 +246,8 @@ class AsyncUDPServerSocket : private AsyncUDPSocket::ReadCallback,
     applyEventCallback();
   }
 
+  bool setTimestamping(int val) { return socket_->setTimestamping(val); }
+
  private:
   // AsyncUDPSocket::ReadCallback
   void getReadBuffer(void** buf, size_t* len) noexcept override {