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

use .Mt to mark up email addresses consistently (part6)

PR: 191174
Submitted by: Franco Fichtner <franco at lastsummer.de>

Update vfs_getopt(9) to reflect 32-bit to 64-bit change from
r224290.

PR: 159324
Submitted by: Brandon Gooch (jamesbrandongooch % gmail ! com)
Approved by: re (kib)

Extend the "vfsopt" mount options for more general use. Make struct
vfsopt and the vfs_buildopts function public, and add some new fields
to struct vfsopt (pos and seen), and new functions vfs_getopt_pos and
vfs_opterror.

Further extend the interface to allow reading options from the kernel
in addition to sending them to the kernel, with vfs_setopt and related
functions.

While this allows the "name=value" option interface to be used for more
than just FS mounts (planned use is for jails), it retains the current
"vfsopt" name and <sys/mount.h> requirement.

Approved by: bz (mentor)

Markup polishing.

Document the mount option handling functions.

Reviewed By: ru