Pullup follwoing revisons to fix build break of ticket 1931 on some archs:

distrib/alpha/cdroms/installcd/Makefile		1.2
distrib/pmax/cdroms/installcd/Makefile		1.2
distrib/prep/cdroms/installcd/Makefile		1.3
distrib/sgimips/cdroms/installcd/Makefile	1.2
distrib/sparc/cdroms/installcd/Makefile		1.2
distrib/sparc64/cdroms/installcd/Makefile	1.14
distrib/sun3/cdroms/installcd/Makefile		1.2
distrib/vax/cdroms/installcd/Makefile		1.2

Use ${CDIMAGE} instead of ${CDBASE}.iso.