Handle updating tooltip text in wxCompositeWindow correctly.

While calling SetToolTip(wxToolTip*) overload already worked correctly for
wxCompositeWindow, using SetToolTip(wxString) did not if a tooltip already
existed, as it didn't use the virtual DoSetToolTip() in this case, resulting
in e.g. impossibility to update wxSpinCtrlDouble tooltip using this method.

Fix this by introducing DoSetToolTipText() virtual which is used by that
overload now and overriding it in wxCompositeWindow.

Also don't override DoSetToolTip() in wxSpinCtrlGenericBase any more, it is
not necessary as it's already done by its base class wxCompositeWindow.

Closes #16595.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@78245 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/window.h

@@ -1312,7 +1312,7 @@ public:
 
 #if wxUSE_TOOLTIPS
         // the easiest way to set a tooltip for a window is to use this method
-    void SetToolTip( const wxString &tip );
+    void SetToolTip( const wxString &tip ) { DoSetToolTipText(tip); }
         // attach a tooltip to the window, pointer can be NULL to remove
         // existing tooltip
     void SetToolTip( wxToolTip *tip ) { DoSetToolTip(tip); }
@@ -1787,6 +1787,7 @@ protected:
     virtual void DoCentre(int dir);
 
 #if wxUSE_TOOLTIPS
+    virtual void DoSetToolTipText( const wxString &tip );
     virtual void DoSetToolTip( wxToolTip *tip );
 #endif // wxUSE_TOOLTIPS