Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

sesutil.8: Polish

- Use right mdoc macros
- Fix synopsis. Some of the optional command modifiers were not optional
after all.
- Sort options

MFC after: 1 week

Add 'sesutil show' subcommand to show enclosure and its contents
in a user-friendly way.

Reviewed by: allanjude, bcr (manpages)
MFC after: 2 weeks
Relnotes: yes
Sponsored by: Klara Inc.
Differential Revision: https://reviews.freebsd.org/D22567

Add libxo(3) support to sesutil(8)

This is useful to simplify parsing "sesutil map"

Submitted by: nikita.kozlov@blade-group.com
MFC after: 3 weeks
Relnotes: yes
Sponsored by: blade

Improve and expand sesutil(8)

- Return an error if no matching device is found when the locate command is run
- Enhance the locate command to be able to address drive bays with no disk, or where the SES controller has not made the mapping to the device name
- Added the fault command, similar to locate, but a different SES property. On some of my controllers locate blinks the activity light, others the fault light. The fault command keeps the fault light on constant.
- Improve the usage() output and use it everywhere
- Added the map command, displays all elements connected to each (or the specified) ses(4) controller
- Added the status command, returns the overall status of the ses(4) controller

Reviewed by: wblock (man page, earlier version)
Approved by: bapt (mentor)
MFC after: 3 weeks
Relnotes: yes
Sponsored by: ScaleEngine Inc.
Differential Revision: https://reviews.freebsd.org/D3580

Add a new sesutil(8) utility

This is an utility for managing SCSI Enclosure Services (SES) device.

For now only one command is supported "locate" which will change the test of the
external LED associated to a given disk.

Usage if the following:
sesutil locate disk [on|off]

Disk can be a device name: "da12" or a special keyword: "all".

Reviewed by: mav
MFC after: 1 month
Relnotes: yes
Sponsored by: gandi.net
Differential Revision: https://reviews.freebsd.org/D3544