Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Modularize the Open Firmware client interface to allow run-time switching
of OFW access semantics, in order to allow future support for real-mode
OF access and flattened device frees. OF client interface modules are
implemented using KOBJ, in a similar way to the PPC PMAP modules.

Because we need Open Firmware to be available before mutexes can be used on
sparc64, changes are also included to allow KOBJ to be used very early in
the boot process by only using the mutex once we know it has been initialized.

Reviewed by: marius, grehan

In openprom_ioctl() ensure appropriate permissions and that data isn't
NULL and doesn't point to a NULL pointer before dereferencing it. This
fixes a panic triggered by Xorg 7.3.

Reported and tested by: Bill Green
MFC after: 3 days

Sync with openfirm(4) and check the return value of malloc() although
this isn't exactly necessary with M_WAITOK.

Instead of "OpenFirmware", "openfirmware", etc. use the official spelling
"Open Firmware" from IEEE 1275 and OpenFirmware.org (no pun intended).

Ok'ed by: tmm

Do a pass over all modules in the kernel and make them return EOPNOTSUPP
for unknown events.

A number of modules return EINVAL in this instance, and I have left
those alone for now and instead taught MOD_QUIESCE to accept this
as "didn't do anything".

Do the dreaded s/dev_t/struct cdev */
Bump __FreeBSD_version accordingly.

Device megapatch 4/6:

Introduce d_version field in struct cdevsw, this must always be
initialized to D_VERSION.

Flip sense of D_NOGIANT flag to D_NEEDGIANT, this involves removing
four D_NOGIANT flags and adding 145 D_NEEDGIANT flags.

Use __FBSDID().
Also some minor style cleanups.

Add a solaris compatible ofw interface for third party software that
expects one to use. Only the functions used by XFree86 are actually
implemented.

Glanced at by: tmm