added the new itemlistbox headers to the Makefile.am
added the new itemlistbox headers to the Makefile.am

OpenTechEngine/CEGUI,ruleless/CEGUI,ruleless/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI,OpenTechEngine/CEGUI,ruleless/CEGUI,OpenTechEngine/CEGUI