Fix harmless unused parameter warning in !wxUSE_GRAPHICS_CONTEXT build.

Rich tooltip tip kind is unused as no tip is drawn in this case.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74494 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/richtooltipg.cpp

@@ -561,6 +561,8 @@ private:
 
         SetShape(path);
 #else // !wxUSE_GRAPHICS_CONTEXT
+        wxUnusedVar(tipKind);
+
         int x = contentSize.x/2,
             yApex = 0,
             dy = 0;