- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

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

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

Use __unused macro instead of a bare void for main().

Suggested by: nectar

nologin(8) does not seem to require any command line parameters,
so remove argc and argv from main() argument.

At the same time, user and tt is not likely to be changed during
execution so mark them const.

This commit should guarantee nologin to pass WARNS=6.

Tested on: i386
MFC After: 1 month

Add standard copyright notice; fix style bugs. (Reported by bde)
Remove NO_NOLOGIN_LOG option now that we're off the root partition.

Forced commit to note that files have been repocopied from
src/sbin/nologin to src/usr.sbin/nologin in preparation for
moving nologin(8) from /sbin to /usr/sbin.

Report login attempts to syslog. Due to the statically-linked nature of
nologin(8), this causes a considerable (100K) increase in the binary size,
so I've added a NO_LOGIN_LOG option which disables this.

While I'm here, s/sizeof(MESSAGE)/sizeof(MESSAGE) - 1/, in order to
avoid writing the string-terminating zero byte.

No complaints from: -current
Approved by: rwatson (mentor)

Reimplement nologin(8) as a C program. This allows us to statically
link it at low cost and avoid environment poisoning attacks associated
with LD_LIBRARY_PATH.

Suggested by: rwatson