qcad: fix library browser

the drawing library of qcad uses qt's database abstract for sqlite.

Somehow the libqsqlite library file is not found in the default
location. As workaround it is copied to the qcad library directory.

pkgs/applications/misc/qcad/default.nix

@@ -61,6 +61,10 @@ mkDerivationWith stdenv.mkDerivation rec {
     cp -r plugins $out/lib/plugins
     cp -r patterns $out/lib/patterns
 
+    # workaround to fix the library browser:
+    rm -r $out/lib/plugins/sqldrivers
+    ln -s -t $out/lib/plugins ${qt5.qtbase}/${qt5.qtbase.qtPluginPrefix}/sqldrivers
+
     install -Dm644 scripts/qcad_icon.svg $out/share/icons/hicolor/scalable/apps/qcad.svg
 
     runHook postInstall