Show busy cursor on eject, improves

2.2.0-RC Eject is very slow in Linux #3795

src/slic3r/GUI/Plater.cpp

@@ -5232,6 +5232,7 @@ void Plater::send_gcode()
 // Called when the Eject button is pressed.
 void Plater::eject_drive()
 {
+    wxBusyCursor wait;
 	wxGetApp().removable_drive_manager()->eject_drive();
 }