Android: fix typo calling onBackPressed() (Bug 4657)

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

@@ -473,7 +473,7 @@ public class SDLActivity extends Activity implements View.OnSystemUiVisibilityCh
 
     // Used to access the system back behavior.
     public void superOnBackPressed() {
-        super.onBackPressed();
+        onBackPressed();
     }
 
     @Override