Drop explicit unsigned from FD_SETSIZE constant

FD_SETSIZE is often used as an argument to select or compared with an
integer file descriptor.  Rather than force 3rd party software to add
explicit casts, just make it a plain (int) constant as on other
operating systems.

Previous discussion:
http://lists.freebsd.org/pipermail/freebsd-standards/2012-July/002410.html
Reduce number of opens by REOM RAID during provider taste.

Instead opening/closing provider by each of metadata classes, do it only
once in core code.  Since for SCSI disks open/close means sending some
SCSI commands to the device, this change reduces taste time.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
Add proto(4): A driver for prototyping and diagnostics.
It exposes I/O resources to user space, so that programs can peek
and poke at the hardware. It does not itself have knowledge about
the hardware device it attaches to.

Sponsored by:	Juniper Networks, Inc.
Add a C libary and a Python module that implements an API similar
to bus_space(9) and that uses the proto(4) driver for talking to
hardware. If the I/O resource is a memory mapped I/O resource,
then mmap(2) will be attempted to avoid read(2)/write(2) overhead.

Sponsored by:	Juniper Networks, Inc.
Turn off various fancy instruction sets, as well as deduplicate some options.
This makes the EFI loader build work with CPUTYPE=native in make.conf on
my Core i5.
Implement legacy interrupts for the AHCI device emulation
according to the method outlined in the AHCI spec.

Tested with FreeBSD 9/10/11 with MSI disabled,
and also NetBSD/amd64 (lightly).

Reviewed by:	neel, tychon
MFC after:	3 weeks
Set the new floating point exception mask correctly

Submitted by:	Keith White <kwhite@site.uottawa.ca>
Revert r263754, re-adding support for hw.bus.devctl_disable.  Breaking
old devd's and thus hosts that get IP addresses from DHCP was too much
of a POLA violation.

The sysctl may be removed again after r263758 has been merged to at
least stable/9 and stable/10, and releases have been cut from those
branches.

Discussed with:	mjg
Reported by:	theraven, rwatson
Remove note about hw.bus.devctl_disable removal, restored
in r265060.

Sponsored by:	The FreeBSD Foundation
Allow a virtual machine to be forcibly reset or powered off. This is done
by adding an argument to the VM_SUSPEND ioctl that specifies how the virtual
machine should be suspended, viz. VM_SUSPEND_RESET or VM_SUSPEND_POWEROFF.

The disposition of VM_SUSPEND is also made available to the exit handler
via the 'u.suspended' member of 'struct vm_exit'.

This capability is exposed via the '--force-reset' and '--force-poweroff'
arguments to /usr/sbin/bhyvectl.

Discussed with:	grehan@
Add dependency for libm to libstdc++. This fixes high -j value builds
when not building with clang.

Submitted by: ian@
Remove redundant include

MFC after:	3 days
Document the -a option that was added in r262424.

Obtained from:	Netflix, Inc.
MFC after:	3 days
Fix formatting of the -a option in usage() to be consistent.

Obtained from:	Netflix, Inc.
MFC after:	3 days
Add standard SYNOPSIS wording, fix typos, contractions and new sentence -> new line.
After r264897 restore the ability to add bootoptions from FDT for
platforms which do not use loaders or kernels that want to hardcode
options or for FDT passed in by loader.

Also fix a build issue by putting the kmdp variable accessed back under
the #ifdef FDT;  we may wish to revisit decision in which case more
code needs changing.

Submitted by:	brooks