Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r237259 r237260 r237329:
Allow users with RO privilege to the device to read the RO attributes. [0]
Add __unused macros to appropriate places in order to allow building
with WARNS=6 on base gcc, gcc46, and clang

PR: bin/167302 [0]
Approved by: cperciva (implicit)

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fix division by zero, causing floating point exception in a drive progress
command.

It was possible to read a value of zero from a busy controller used
as the divisor to calculate the remaining rebuild time.

Reported by: Pavel Udovenko <udovenko att nic.ru>
Discussed with: jhb
Approved by: kib (mentor)
MFC after: 1 week

Fix typo.

ntroduce mfiutil, a basic utility for managing LSI SAS-RAID & Dell PERC5/6
controllers. Controller, array, and drive status can be checked, basic
attributes can be changed, and arrays and spares can be created and deleted.
Controller firmware can also be flashed.

This does not replace MegaCLI, found in ports, as that is officially sanctioned
and supported by LSI and includes vastly more functionality. However, mfiutil
is open source and guaranteed to provide basic functionality, which can be
especially useful if you have a problem and can't get MegaCLI to work.

Approved by: re
Obtained from: Yahoo! Inc.