avformat/mp3dec: make generic index mode the default

It's the most useful mode, because it seeks accurately, and does not
break features like gapless audio.

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

libavformat/mp3dec.c

@@ -337,7 +337,7 @@ static int mp3_read_header(AVFormatContext *s)
     int i;
 
     if (mp3->usetoc < 0)
-        mp3->usetoc = 0;
+        mp3->usetoc = 2;
 
     st = avformat_new_stream(s, NULL);
     if (!st)

tests/fate/gapless.mak

@@ -1,5 +1,5 @@
 FATE_GAPLESS-$(CONFIG_MP3_DEMUXER) += fate-gapless-mp3 fate-gapless-mp3-toc fate-gapless-mp3-notoc
-fate-gapless-mp3: CMD = gapless $(TARGET_SAMPLES)/gapless/gapless.mp3 "-usetoc 2"
+fate-gapless-mp3: CMD = gapless $(TARGET_SAMPLES)/gapless/gapless.mp3
 fate-gapless-mp3-toc: CMD = gapless $(TARGET_SAMPLES)/gapless/gapless.mp3 "-usetoc 1"
 fate-gapless-mp3-notoc: CMD = gapless $(TARGET_SAMPLES)/gapless/gapless.mp3 "-usetoc 0"