Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

- Add descriptions to most of the rc scripts. Those are mostly taken from their
daemon's manpage and probably improved.
- Consistently use "filesystem" not "file system".

Approved by: bapt, brueffer
Differential Revision: D452

Ignore per-mdN settings in mdconfig[2] startup

PR: base/189696
Submitted by: ganael.laplanche@martymac.org
MFC after: 3 days
X-MFC-to: stable/10 stable/9

Loosen the processing of *_IF_aliasN vars to be less strict. Previously,
the first alias had to be _alias0 and processing stopped at the first non-
defined variable (preventing gaps). Allowing gaps gives the administrator
the ability to group aliases in an adhoc manner and also lifts the
requirement to renumber aliases simply to comment-out an existing one.
Aliases are processed in numerical ascending order.

Discussed on: -rc
MFC after: 1 week

Remove trailing white space. No functional changes.

As previously discussed, add the svn:executable property to all scripts

Use $required_modules wherever suitable. Use load_kld() in special
cases. So we get rid of quite a few lines of duplicated code.

Don't load geom_md.ko if there is no need to.

Remove the require_kld function I just committed and replace with a nicer solution.

Reported by: pjd
Approved by: cperciva

Add two new scripts (mdconfig/mdconfig2) to replace old ramdisk{,-own}
scripts. These scripts handle vnode backed md(4) devices.

Old ramdisk{,-own} scripts will stay a bit in CVS to allow some time for
migration since variable names have changed (ramdisk_* -> mdconfig_*).

Two new variables have been introduced to be able to populate the md(4)
device once it has been mounted (mdconfig_*_files and mdconfig_*_cmd).

Use should be as easy as:

mdconfig_md0="-t malloc -s 10m"
mdconfig_md1="-t vnode -f /var/foo.img"

See rc.conf(5) for more information and description of the additional
variables.

Approved by: cperciva