Fix expected mouse event sizes

Commit fefb9816a9 modified mouse events
serialization. The server-side parsing was updated to correctly read the
position, but the expected size of these events was not updated.

As a result, the server might try to parse incomplete events, leading
to BufferUnderflowException.

Fixes
<https://github.com/Genymobile/scrcpy/issues/350#issuecomment-456298816>.

server/src/main/java/com/genymobile/scrcpy/ControlEventReader.java

@@ -9,8 +9,8 @@ import java.nio.charset.StandardCharsets;
 public class ControlEventReader {
 
     private static final int KEYCODE_PAYLOAD_LENGTH = 9;
-    private static final int MOUSE_PAYLOAD_LENGTH = 13;
-    private static final int SCROLL_PAYLOAD_LENGTH = 16;
+    private static final int MOUSE_PAYLOAD_LENGTH = 17;
+    private static final int SCROLL_PAYLOAD_LENGTH = 20;
     private static final int COMMAND_PAYLOAD_LENGTH = 1;
 
     public static final int TEXT_MAX_LENGTH = 300;