Debloat IVideoDriver and IrrlichtDevice includes (#15080)

As the project grows, compile time will not go down unless the header mess
is cleaned up one by one to only include exactly what's needed.

src/gui/guiFormSpecMenu.h

@@ -37,6 +37,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "util/string.h"
 #include "util/enriched_string.h"
 #include "StyleSpec.h"
+#include <ICursorControl.h> // gui::ECURSOR_ICON
 #include <IGUIStaticText.h>
 
 class InventoryManager;