avcodec/mpeg4audio: add some padding/alignment to MAX_PCE_SIZE

This avoids potential accesses over the end
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mpeg4audio.h

@@ -102,7 +102,7 @@ enum AudioObjectType {
     AOT_USAC,                  ///< N                       Unified Speech and Audio Coding
 };
 
-#define MAX_PCE_SIZE 304 ///<Maximum size of a PCE including the 3-bit ID_PCE
+#define MAX_PCE_SIZE 320 ///<Maximum size of a PCE including the 3-bit ID_PCE
                          ///<marker and the comment
 
 int avpriv_copy_pce_data(PutBitContext *pb, GetBitContext *gb);