avcodec: fix memory leak

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/codec/avcodec/audio.c

@@ -368,6 +368,7 @@ static block_t *DecodeAudio( decoder_t *p_dec, block_t **pp_block )
         p_block = vlc_av_frame_Wrap(frame);
         if (unlikely(p_block == NULL))
             goto drop;
+        frame = NULL;
     }
 
     if (p_sys->b_extract)
@@ -403,6 +404,7 @@ static block_t *DecodeAudio( decoder_t *p_dec, block_t **pp_block )
 end:
     *pp_block = NULL;
 drop:
+    av_frame_free(&frame);
     if( p_block != NULL )
         block_Release(p_block);
     return NULL;