Bug 1410456 - remove an unused variable that produces a compile warning. r=padenot

MozReview-Commit-ID: IerCYxsDQFX

--HG--
extra : rebase_source : bd6384189a686fec9c9b43bdab4e5b9c14a95416

media/libcubeb/src/cubeb_opensl.c

@@ -236,7 +236,6 @@ static void
 play_callback(SLPlayItf caller, void * user_ptr, SLuint32 event)
 {
   cubeb_stream * stm = user_ptr;
-  int draining;
   assert(stm);
   switch (event) {
     case SL_PLAYEVENT_HEADATMARKER: