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

MozReview-Commit-ID: Hf7Od37bnzX

--HG--
extra : rebase_source : d53cbf4ef6f79ee9caac4e74a67f67a2e441669f

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: