Sysinst support for installing source sets

[Andreas Gustafsson <gson%gson.org@localhost>]

I have a patch to sysinst which adds the ability to install source
sets, and I'm wondering if I should commit it.

The main reason I wrote this was to make it easy for anita
(http://www.gson.org/netbsd/anita/) to include the source sets in
automated installs, to facilitate source-level debugging of any
failing automated tests, but I think it would also be useful to human
users, and it would fix half of an ancient open PR, install/9582
(http://gnats.netbsd.org/9582).

There are two user-visible changes.  First, if you choose "Custom
installation", you will see an additional group called "Source sets"
similar to the existing group of "X11 sets", and have the option of
enabling all or part of it.  Choosing "Full installation" still only
does a full binary installation, so that that option still works with
install ISOs that do not contain source sets.  It is possible to shoot
yourself in the foot by explicitly asking to install the source sets
from an ISO that does not have them, but I'm not sure if anything can
be done about that without also removing the ability to install the
source sets via FTP, and it's not like you can't already get into
similar trouble with the X sets, too.

Second, because source sets reside in a different directory than the
binary sets both on install media and on FTP sites (as a result of
being machine independent), sysinst now lets you enter a separate
"Binary set directory" and "Source set directory" instead of just a
"Set directory".  A default source set directory is provided and will
be correct in the typical cases, such as installing by FTP from
ftp.netbsd.org or from an ISO built using "build.sh iso-image-source".

The patch contains English message strings for the new set names and
prompts, and uneducated guesses at parts of the other translations,
but some other translations are missing and will display the English
text.  If you know German, French, Spanish, or Polish, please review
the translations and send me any corrections or additions.

The patch is available at:

  http://www.gson.org/netbsd/patches/sysinst-source.patch

-- 
Andreas Gustafsson, gson%gson.org@localhost