fsck_lfs(8): add -i to SYNOPSIS, 'file system' police, bump date

Document the -a and -i flags.

Revert version 1.111 of sysinst/disks.c, which caused sysinst to
create lfs fstab entries with fsck disabled, and instead patch
fsck_lfs to exit successfully without doing anything when given the -p
(bootup preen) option. If you really want to do fsck_lfs -p, you can
do fsck_lfs -f -p to make it go.

This has been sitting in my todo queue since February 2010 and was
ok'd by the committer at the time. The original commit was based on
this post:
http://mail-index.netbsd.org/tech-kern/2010/02/09/msg007306.html

and I remain unconvinced that it's the right thing, but we can at
least do it properly and not ship a sysinst with -7 that creates
permanently wrong fstab files.

Note that this may cause problems for anyone who's taken -p out of the
bootup fsck flags; but doing that is wrong, so don't.

branches: 1.24.2;
Merge riastradh-drm2 to HEAD.

Use Mt for email addresses.

branches: 1.22.6; 1.22.12; 1.22.16;
Fix markup.

branches: 1.21.4;
Disable userid to username lookups by default. Add a -U flag to perform them.
In single user mode lookups that involve the network might not work and they
slow down fsck.

branches: 1.20.4; 1.20.20;
Quote a word that would otherwise be interpreted as macro;
increase width argument to .Bl so that all options fit.

Bump date for new -q; use Dq; capitalize NetBSD
in the usual way; new sentence, new line; some nits.

Document "-f" (force check) flag. Implement and document "-q" (quiet).

branches: 1.17.2;
Improve description of -b and -m.

Document -m. It was already there, only commented out.
Bump date.

Addresses PR 26067 by Kouichirou Hiratsuka.

Move UCB-licensed code from 4-clause to 3-clause licence.

Patches provided by Joel Baker in PR 22308, verified by myself.

Bump date for last.

Add working writing ability to fsck_lfs, including roll-forward, based on
a partial-segment writer ported from the kernel.

.Nm does not need a dummy argument ("") before punctuation or
for correct formatting of the SYNOPSIS any longer.

Use An, Aq for author markup.

New sentence, new line. By Robert Elz with minimal fixes.

Generate <>& symbolically. I'm avoiding .../dist/... directories for now.

Edit -mdoc usage.

* There is no -indent option to .Bd or .Bl, although you would
never know that from its frequent use in this tree. There is a
"-offset indent" combination that makes sense, and you can certainly
say "-width indent".

* Also, you can't markup the -width option argument, tho you CAN
use a callable macro. So "-width Ar filename" doesn't make sense,
but either "-width Ar" or "-width filename" does, as might something
like "-width xxfilename" for a little extra space.

* There are a lot of needlessly complex hanging tag macros in man4 used
to create simple item lists. Those should be simplified one of these
days before someone copies and edits yet another man4 page.

Sort sections, use standard section headers.

Drop arguments of .Os.

Xref newfs_lfs instead of newlfs; whitespace fixes while I'm here.

fix up various .Nm abuses:
- keep the case consistent between the actual name and what's referenced.
e.g, if it's `foo', don't use '.Nm Foo' at the start of a sentence.
- remove unnecessary `.Nm foo' after the first occurrence (except for
using `.Nm ""' if there's stuff following, or for the 2nd and so on
occurrences in a SYNOPSIS
- use Sx, Ic, Li, Em, Sq, and Xr as appropriate

branches: 1.3.4;
fsck_lfs can now write to the filesystem, allowing it to correct most
(though still not all) errors in a damaged lfs. Segment byte accounting
is corrected in pass 5. "fsck_lfs -p" will do a partial roll-forward,
verifying the checkpoint from the newer superblock. fscknames[] is
updated so that fsck knows about fsck_lfs.

"LFS" really stands for "Log-*structured* File System"

Initial checkin of fsck_lfs. This version cannot do any repair (-p flag
does nothing, and one of -p or -n is required) but can be useful as a
diagnostic tool.