Android: remove hard-coded constant for Samsung DeX (no op!)

12290 = 0x3002 = SOURCE_MOUSE | SOURCE_TOUCHSCREEN

SOURCE_MOUSE            Constant Value: 8194 (0x00002002)
SOURCE_TOUCHSCREEN      Constant Value: 4098 (0x00001002)
SOURCE_CLASS_POINTER    Constant Value: 2    (0x00000002)

https://developer.android.com/reference/android/view/InputDevice.html

android-project/app/src/main/java/org/libsdl/app/SDLActivity.java

@@ -1770,7 +1770,10 @@ class SDLSurface extends SurfaceView implements SurfaceHolder.Callback,
         float x,y,p;
 
         // 12290 = Samsung DeX mode desktop mouse
-        if ((event.getSource() == InputDevice.SOURCE_MOUSE || event.getSource() == 12290) && SDLActivity.mSeparateMouseAndTouch) {
+        // 12290 = 0x3002 = 0x2002 | 0x1002 = SOURCE_MOUSE | SOURCE_TOUCHSCREEN
+        // 0x2   = SOURCE_CLASS_POINTER
+        if ((event.getSource() == InputDevice.SOURCE_MOUSE || event.getSource() == (InputDevice.SOURCE_MOUSE | InputDevice.SOURCE_TOUCHSCREEN))
+                && SDLActivity.mSeparateMouseAndTouch) {
             try {
                 mouseButton = (Integer) event.getClass().getMethod("getButtonState").invoke(event);
             } catch(Exception e) {