Add getEventBase() to AsyncUDPSocket

Summary: Add an event base getter for AsyncUDPSocket similar to the other socket classes.

Reviewed By: knekritz

Differential Revision: D5498587

fbshipit-source-id: ac3179e03485328417ed9863f6bb790de7c691cb

folly/io/async/AsyncUDPSocket.h

@@ -158,6 +158,10 @@ class AsyncUDPSocket : public EventHandler {
     reuseAddr_ = reuseAddr;
   }
 
+  EventBase* getEventBase() const {
+    return eventBase_;
+  }
+
  private:
   AsyncUDPSocket(const AsyncUDPSocket&) = delete;
   AsyncUDPSocket& operator=(const AsyncUDPSocket&) = delete;