release directories and naming for install images, live images, and isos

[Jeff Rizzo <riz%netbsd.org@localhost>]

I wanted to get some feedback from people before making changes in this 
area.

I'm preparing this with an eye towards the 6.0 release, so timely 
feedback would be helpful.  I'd like to make any changes within a week 
or so.

Right now, we have some different release collection targets for 
build.sh:  iso-image, install-image, which by default create ISOs with 
sets and a bootable fs image with sets, respectively and live-image, 
which creates a bootable fs image without sets.  (install-image and 
live-image are x86-only at the moment, but there's no reason other 
arches couldn't be made with the same framework;  they were added 
recently by tsutsui@)

The naming scheme for ISO images was changed recently, to better reflect 
OS, version, and architecture.  ("NetBSD-6.99.4-macppc.iso" as opposed 
to the old "macppccd.iso").  The install-image and live-image targets 
still have an old-style naming;  "amd64inst.img.gz".

The iso-image target installs its output into $RELEASEDIR/iso, while 
install-image installs into 
$RELEASEDIR/$RELEASEMACHINEDIR/installation;  while this doesn't matter 
much for individual builds, it confuses things a bit when building 
*everything*.  There isn't one directory where all the big release 
binaries (iso, fs image) go.  To make things a bit better organized, I 
propose to make the following changes:

- name images a more descriptive name.  
("NetBSD-6.99.4-amd64-inst.img.gz", for example)
- install images and ISOs in $RELEASEDIR/images, to keep them in a 
single place.
- create a symlink $RELEASEDIR/images -> $RELEASEDIR/iso so people used 
to looking for ISOs don't get lost
- create symlinks for ISOs and images into 
$RELEASEMACHINEDIR/installation/cdrom and 
$RELEASEMACHINEDIR/installation/install-image respectively
- have these changes pulled up for 6.0 once stable.

I've looked into the makefiles, and this should be doable in a few 
minutes, plus some time for test builds.  Does anyone have any comments 
or criticism?

Thanks,
+j