Add hack to Resolve all symbols when painting.

Seems rather expensive, but this is what the Legacy canvas did.
In fairness, it does check the last-mod-date of the libraries
and skips it if they haven't changed.

Fixes: lp:1798446
* https://bugs.launchpad.net/kicad/+bug/1798446

eeschema/sch_draw_panel.cpp

@@ -694,6 +694,9 @@ void SCH_DRAW_PANEL::onPaint( wxPaintEvent& aEvent )
         // (depending on platforms). Do nothing in this case
         return;
 
+    // Ensure links are up to date, even if a library was reloaded for some reason:
+    static_cast<SCH_SCREEN*>( GetScreen() )->UpdateSymbolLinks();
+
     if( m_painter )
         static_cast<KIGFX::SCH_PAINTER*>(m_painter.get())->GetSettings()->ImportLegacyColors( nullptr );