App: Add None=0 to enumeration

Addresses Coverity CID 356649, uninitialized scalar.

src/App/Link.h

@@ -332,6 +332,8 @@ public:
      * Multiple options can be combined by bitwise or operator
      */
     enum class OnChangeCopyOptions {
+        /// No options set
+        None = 0,
         /// If set, then exclude the input from object list to copy on change, or else, include the input object.
         Exclude = 1,
         /// If set , then apply the setting to all links to the input object, or else, apply only to this link.

src/Gui/ViewProviderLink.cpp

@@ -2447,7 +2447,7 @@ void ViewProviderLink::setupContextMenu(QMenu* menu, QObject* receiver, const ch
                     bool applyAll = box->isChecked();
                     App::LinkParams::setCopyOnChangeApplyToAll(applyAll);
 
-                    App::Link::OnChangeCopyOptions options;
+                    App::Link::OnChangeCopyOptions options {App::Link::OnChangeCopyOptions::None};
                     if (applyAll)
                         options |= App::Link::OnChangeCopyOptions::ApplyAll;