Fix compiler warnings.
Introduce new structure sfstat for collecting sendfile's statistics
and remove corresponding fields from struct mbstat. Use PCPU counters
and SFSTAT_INC() macro for update these statistics.

Discussed with:	glebius
MFi386: add ddb "show sysregs" command.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Move the Raspberry Pi low level options out of the kernel config and into
std.rpi + std.bcm2835.

Reviewed by:	imp
When stopping pfsync, remove the pfsync interface's syncpeer setting.

MFC after:	3 days
Nuke "systat -mbuf". It was broken since FreeBSD 5, and since there
haven't been any complaints, no one used it.
Nuke mbstat. It wasn't used for mbuf statistics since FreeBSD 5.

Now that r253351 moved sendfile() stats to a separate struct, the
last field used in mbstat is m_mcfail, which is updated, but never
read or obtained from userland.
Add IBM ServeRAID M5110 to the hardware list.
This is a rebranded MegaRAID SAS 2208 [Thunderbolt] found e.g. on x3550 M4.

Reported by:	Ilia Noskov <noskov@nic.ru>
MFC after:	3 days
Include sys/systm.h after sys/param.h.

Suggested by:	pluknet
Fix an argument reversal in calls to scsi_read_element_status().

Reported by:	Ulrich Spoerlein <uqs@FreeBSD.org>
MFC after:	3 days
Make some improvements to r253322 to really rescan target, not a bus.
Add there and in two more places checks for NULL on xpt_alloc_ccb_nowait().
Add -n flag for compatibility with Linux version of mount(8).

Reviewed by: freebsd-fs, eadler, mckusick, jh, wblock
Silent warnings.
Add urtwnfw.
libc: name passed into __setenv is not necessarily NUL-terminated

That's particularly true when __setenv is called from __merge_environ.

MFC after:	4 days
Add missing header needed by sleep(3).
Use MAN= instead of NO_MAN=

For some reason it still tries to install a priv.1 when using NO_MAN,
even though there isn't one yet.
Need to define NO_MAN here.
Sweep unused nlist entries.

Sponsored by:	Nginx, Inc.
Workaround some broken BIOSes that specify edge-sensitive but active-low
settings for ACPI-enumerated serial ports by forcing any IRQs that use
an ISA IRQ value with these settings to active-high instead of active-low.

This is known to occur with the BIOS on an Intel D2500CCE motherboard.

Tested by:	Robert Ames <robertames@hotmail.com>, lev
Submitted by:	Juergen Weiss weiss at uni-mainz.de (original patch)