Fix typo

Summary:
Fix typo

(Note: this ignores all push blocking failures!)

Reviewed By: mokomull

Differential Revision: D21056053

fbshipit-source-id: 3bf4295f9c6be1c50cdc64f6bbdf1b34cce6bece

folly/io/async/AsyncUDPSocket.h

@@ -269,7 +269,7 @@ class AsyncUDPSocket : public EventHandler {
   }
 
   /**
-   * Set SO_SNDBUG option on the socket, if not zero. Default is zero.
+   * Set SO_SNDBUF option on the socket, if not zero. Default is zero.
    */
   virtual void setSndBuf(int sndBuf) {
     sndBuf_ = sndBuf;