Fix a bug in calculating the VP8 Payload Descriptor size

src/org/jitsi/impl/neomedia/codec/video/vp8/DePacketizer.java

@@ -283,7 +283,7 @@ public static int getSize(byte[] input, int offset) throws Exception
             if((input[offset] & X_BIT) == 0)
                 return 1;
 
-            int size = 1;
+            int size = 2;
             if((input[offset+1] & I_BIT) != 0)
             {
                 size++;