clean up flags++ instances around getopt()
ok florian

Replace <sys/param.h> with <limits.h> and other less dirty headers where
possible. Annotate <sys/param.h> lines with their current reasons. Switch
to PATH_MAX, NGROUPS_MAX, HOST_NAME_MAX+1, LOGIN_NAME_MAX, etc. Change
MIN() and MAX() to local definitions of MINIMUM() and MAXIMUM() where
sensible to avoid pulling in the pollution. These are the files confirmed
through binary verification.
ok guenther, millert, doug (helped with the verification protocol)

ctype improvements; checked by okan

Fix calls to printf-like functions which passed a non-fixed string
as the format and no variable args.
Replace "%#0.*X" with "%#.*X": the zero-fill flag is ignored/implied
on numeric conversions when a precision is specified.

ok jung@ millert@ krw@

When a passwd(5) file is not available, fall back to master.passwd(5).
That's useful because the latter is needed for passwd-maps, anyway.
Make the master.passwd file name configurable in the same way as passwd.

While here, do a bit of cleanup:
- Drop the HOSTS, PASSWD, GROUP, NETID #defines:
They are used nowhere else and serve no purpose.
- Use err(3), it's simpler and more precise than fprintf(3)+goto.
- Drop a debug statement forgotten a decade ago.
- In the manual, improve .Nd, DESCRIPTION and .Xrs.

Originally triggered by edd@'s gripes with our yp implementation.
Regarding the manual, using many tweaks from jmc@.

"I like this" ajacoutot@
"I think it's a good idea" edd@
"no opinion", "you decide" deraadt@

rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable). these days, people use source. these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

sort flags in synopsis, usage, and description.

correct pathnames reported; pr#5742

spreading the lint love (very minimal things..)

knf

protos and repairs

remove clause 3 and 4. -moj

-Wall cleanup: trim unused vars, better err() message in stdhosts,
and constify rcsid[]

deraadt@ ok

bunch more careful tweaks

4344 lines of KNF diff

some more KNF and -Wall

indent

pull in prototypes

need string.h

getopt(3) returns -1 when out of args, not EOF, whee!

$OpenBSD$ tag and few spelling errors

Added in stuff from 960121. Fixed several bugs in ypxfr.