avcodec/hevc_cabac: decrease CABAC_MAX_BIN

Prevents shifts with undefined behavior

Fixes CID1206634
Fixes CID1206635
Fixed CID1206636

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

libavcodec/hevc_cabac.c

@@ -27,7 +27,7 @@
 #include "cabac_functions.h"
 #include "hevc.h"
 
-#define CABAC_MAX_BIN 100
+#define CABAC_MAX_BIN 31
 
 /**
  * number of bin by SyntaxElement.