Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

The last big commit: let usr.sbin/ use WARNS=6 by default.

Remove kludges intended to support src trees with partial obj trees.

Discussed with: ru

Remove MAINTAINER= lines from individual Makefiles in favor of the
MAINTAINER file (which already had entries for sendmail).

Update build infrastructure for sendmail 8.12.

Perform a major cleanup of the usr.sbin Makefiles.
These are not perfectly in agreement with each other style-wise, but they
are orders of orders of magnitude more consistent style-wise than before.

- Backout botched attempt to introduce MANSECT feature.
- MAN[1-9] -> MAN.

Set the default manual section for usr.sbin/ to 8.

Add a MAINTAINER= line so people know who to blame

Style fixes

Give users a way to alter the sendmail (and related utilities) build
environment so they can enable functionality such as SASL, LDAP, Hesiod.

The rest of the changes needed to support the new version of sendmail (8.11.0).
Beyond changes to the build system, this includes fixing up the sample
freebsd.mc configuration for changes in defaults and syntax, removing
outdated documentation, and updating the release notes.

Add snprintf.c to SRCS so that the function quad_to_string exists. The
snprintf function itself is still #ifdef'd out by conf.h. This allows this
program to link when compiled without optimization. With optimization,
the call to quad_to_string gets removed by the compiler. Unfortunately
the linker still links in the quad_to_string function even though it
isn't called. 8-(

Use sendmail-8.9.1 makemap