Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

MFC revisions 268860, 268863:
r268860: Minor enhancements, bug fixes, and man-page adjustments.
r268863: Bump .Dd in manual

Reported by: lme
Approved by: re (gjb)

MFC r257824,257826-257830,258411: Updates to sysrc(8)
257824: Fix a bug with `-d' form working as documented
257826: Add `--version' long option
257827: Add a `-c' option for `check only'
257828: Comments and whitespace
257829: Fix a bug with `-e' introduced by above 257828
257830: Document SYSRC_VERBOSE enviroment variable in the manual
258411: Revert the above 257830 (both merged to get .Dd bump in man-page)

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

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

Fix typos in the BSD License.

Do not inherit $SYSRC_VERBOSE from operating environment. The concern is
that when a user (such as myself) which has SYSRC_VERBOSE=1 in his/her
~/.bash_profile or such that when they are told to execute a command like:

hostname `sysrc -n hostname`

NOTE: To activate a recently configured hostname.

If $SYSRC_VERBOSE is set, then POLA is violated because the output of sysrc
is indirectly influenced (making for an inconsistent experience).

Mirror the changes made in SVN r240798:

Replace "( : ${var?} )" syntax with better "[ ${var+set} ]" syntax.

Reviewed by: adrian (co-mentor)
Approved by: adrian (co-mentor)

Import sysutils/sysrc from the ports tree (current version 5.1). Importing
disconnected under the WITH_BSDCONFIG flag (a good idea since this version of
sysrc(8) indeed requires the `sysrc.subr' module installed by bsdconfig(8)).

Multiple reasons sysrc should not simply continue to live in ports. The most
important being that it is tightly coupled with the base.

Approved by: adrian (co-mentor)