added stub for void touch_ui_selection_none in MLOGestureEngine

Change-Id: I45f957863dc26b2ef40bdfed04cb689325f5b170
Reviewed-on: https://gerrit.libreoffice.org/6492Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>

ios/shared/ios_sharedlo/objective_c/gestures/MLOGestureEngine.m

@@ -470,3 +470,7 @@ void touch_ui_selection_start(MLOSelectionKind kind,
               rectangles[i].origin.y);
     }
 }
+
+void touch_ui_selection_none(){
+    // STUB
+}
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