Determine whether to build clang and its bootstrap tools the same
way. This allows a clang bootstrap to happen, even when WITHOUT_CLANG
is defined. This is a minimal version of a more extensive change which
can be MFC'd more easily. However, we have to also test to see if
we're building clang as not cc, since the bootstrap for that needs
these cross tools and it is easier to build them in just one place.

MFC after: 1 week
Up the minimum system to build FreeBSD current to 8.0-RELEASE. The
issues with vendors that needed 7.x support have been resolved. Many
vendors are still using 8.x build platforms, however, so bumping this
up to 9.0 will have to wait until that is resolved. Actual support for
building from 8.x still relies on those vendors fixing bugs that are
present as most developers have moved onto 9.x or newer platforms.

Reviewed by: marcel@
We no longer support upgrading from FreeBSD 4, so we don't need the
NOMAN and NOSHARED defines here. They have been obsolete for almost a
decade anyway.
Check the right file for pwcache_groupdb.
Don't apply ctf conversions in POSIX mode. These can't happen there
because they pollute the POSIX environment, which doens't allow
for these extentions. ctf conversions are really only relevant when
used in coordination with the rest of the bsd*.mk system anyway.
Leave them in place for the normal, non-posix enviornment since
they are quite useful there.
NO_MAN= has been deprecated in favor of MAN= for some time, go ahead
and finish the job. ncurses is now the only Makefile in the tree that
uses it since it wasn't a simple mechanical change, and will be
addressed in a future commit.
In tree makefile shouldn't be setting policy piecemeal. Don't set
NO_MANCOMPRESS here.
Convert NO_MANCOMPRESS to normal convention.