Fix termination of mov_ch_layouts_wav array lookup

Problem found using ASAN.
In some case, the ff_mov_get_channel_layout_tag function will not find 0
as termination for lookup in the array mov_ch_layouts_wav.

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

libavformat/mov_chan.c

@@ -426,6 +426,7 @@ static const enum MovChannelLayoutTag mov_ch_layouts_wav[] = {
     MOV_CH_LAYOUT_MPEG_7_1_A,
     MOV_CH_LAYOUT_MPEG_7_1_C,
     MOV_CH_LAYOUT_SMPTE_DTV,
+    0,
 };
 
 static const struct {