atrac3: switch to av_assert

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/atrac3.c

@@ -609,7 +609,7 @@ static void reverseMatrixing(float *su1, float *su2, int *pPrevCode, int *pCurrC
                 }
                 break;
             default:
-                assert(0);
+                av_assert1(0);
         }
     }
 }