add description & deps for gpu-firmware-base set.

Deprecate extsrc/, EXTSRCSRCDIR, MKEXTSRC

Remove support for building extsrc/:
1. Makefile: remove do-extsrc target.
2. build.sh: remove options -y and -Y extsrcdir.
3. distrib/sets: remove support for extsrc in various tools
including the options -L ext and -y, and the extsrc sets.
4. doc/BUILDING.mdoc: remove docs for extsrc/, EXTSRCSRCDIR, MKEXTSRC (etc)
5. bsd.own.mk and various Makefiles: remove support for extsrc/,
EXTSRCSRCDIR, MKEXTSRC.

As proposed on tech-kern and tech-userlevel on 2022-01-07
and followed up on 2022-08-21.

fix various small typos, mainly in comments.

s/progam/program/

Reintroduce the support of MKCATPAGES

Requested by <mrg>

Remove catman pages support

No longer relevant after the MKCATPAGES removal.

Separate devicetree .dts -> .dtb building from kernel builds. They are now
part of a separate set, "dtb.tgz", and only built when MKDTB=yes. This
defaults to yes for earmv[67]* and aarch64, and no everywhere else.

PR misc/46937: add modules package, from Lloyd Parkes.

Fix typo in via openchrome driver description (no "s")

Add comment/description for new packages

Don't install YP headers when MKYP=no

Remove the isdn sets from syspkg, now that they have no user left.

Remove dhclient from the base system.

Discussed here:
https://mail-index.netbsd.org/tech-userlevel/2018/06/21/msg011233.html

branches: 1.18.30; 1.18.32;
add TPM sets.

branches: 1.17.4; 1.17.10;
set fixes for SASLC

Add libsaslc examples.

branches: 1.15.2;
Support "extsrc", externally added programs and libraries. Users can write
their own reach-overs, cross-build, install, and get set files just like base
and X11 / X.org. (These sets are not included as TNF releases.)

Remove LKMs and switch to the module framework, pass 1.

Proposed on tech-kern@.

Build and install modules into /kernel/modules. Each module gets a
directory for properties, blobs, etc. It's not fixed in stone and
can easily be changed if there are issues with the location/layout.

branches: 1.12.12; 1.12.14;
Add read-only support for SGI's Extent File System.

Reviewed by pooka@.

While it was nice to re-add the html documentation for ntp,
the comment line had never been removed. Thus adding a
second one was not correct.

Keep the nicer-looking one and remove the newer one. build.sh syspkg
now completes for me.

PR/25482
reinstate NTP html pages (sans gif's/img tags).
The important man pages are now generated by autogen and
thus match again the code again.

more uucp removal

More krb4 removal.

Add support for new ipf and pf syspkgs.

delete sushi records.

Add flist for BIND 9 HTML documentation.

branches: 1.4.6;
Finer-grained syspkgs to save space on tiny systems: move
calendar(1)-related and RPC-related files to their own packages.
Move the termcap(5) database to its own package, also.

Add comments and descriptions for the following system packages:

base-magic-share
base-ppp-lkm
base-rescue-root
base-termcap-share
base-vfs-lkm
comp-c-shlib
comp-fortran-shlib

Put the example fstab files into their own system package in the misc
category (since they're listed in the misc/mi set list), rather than
a system package under base.

Add a comment and a description for the new system package.

Add the comments file, which is a single file containing all the COMMENT
file entries from the syspkg hierarchy, brought up to date to include some
that had been missed out.

Add the descrs file, which is a single file containing all the DESCR
file entries from the syspkg hierarchy, brought up to date to include some
that had been missed out.

Thanks to Jim Wise for all the work that went into the syspkg sets.

Add the attrs file, which is a single file to which can be added
attributes (like preserve).

Add a regpkg script, which allows a single system package to be
registered, based simply on its setname and syspkg name. All the
information is gleaned from the lists files by means of scripts, no
source tree is needed. The version number for the system package is
calculated automatically, based on the most recent mtime of the files
that constitute a system package.

Add a regpkgset script, to register all the system packages in a set.
The set names recognised are "all", "base", "comp", "etc", "games",
"man", "misc", "text".