Update the blurb at the top of the script that describes where the

Update the blurb at the top of the script that describes where the
port is up to and that to do.

Change MACHINE to MACHINE_ARCH so that a symlink can be created to this
file and have the bootstrap work for other NetBSD ports.

Make the csu directory non-optional and build it immediately after
building gcc which *needs* the new csu files. The link spec for gcc
on FreeBSD/Alpha differs from the NetBSD/Alpha version. I decided that
since this is FreeBSD, it should have a FreeBSD flavour and it makes sense
to keep compatibility with other FreeBSD implementations - in this case
FreeBSD/i386-elf.