mpeg12: disable checked reader.

overreads in mpeg12 are not possible
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mpeg12.c

@@ -25,6 +25,8 @@
  * MPEG-1/2 decoder
  */
 
+#define UNCHECKED_BITSTREAM_READER 1
+
 //#define DEBUG
 #include "internal.h"
 #include "avcodec.h"