lavf/img2dec: Skip SOF size when probing jpeg.

Fixes auto-detection for some resolutions.
Reported-by: Clément Bœsch

libavformat/img2dec.c

@@ -709,6 +709,7 @@ static int jpeg_probe(AVProbeData *p)
         case 0xC5:
         case 0xC6:
         case 0xC7:
+            i += AV_RB16(&b[i + 2]) + 1;
             if (state != 0xD8)
                 return 0;
             state = 0xC0;