kde5.breeze-icons: propagate Qt SVG plugin

Necessary to render icons in applications that don't already depend on
this Qt module.

pkgs/desktops/kde-5/frameworks/breeze-icons.nix

@@ -8,4 +8,5 @@ kdeFramework {
   outputs = [ "out" ];
   nativeBuildInputs = [ extra-cmake-modules ];
   propagatedBuildInputs = [ qtsvg ];
+  propagatedUserEnvPkgs = [ qtsvg.out ];
 }