Solaris, narrow down the platforms, and use specific inclusion rather
than disclusion: mark them as ONLY_FOR_PLATFORM=SunOS-*-*, rather
than NOT_FOR_PLATFORM=NetBSD-*-*.
man page. This is what's done in NetBSD, and is more in keeping with the
rest of the suite of rcs programs: rcsclean, rcsdiff, and rcsmerge.
Pointed out by Luke Mewburn.