- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r257334, r257336, r257337, r257338, r257341, r257342, r257343, r257370,
r257368, r257416

Hints-only devices should return BUS_PROBE_NOWILDCARD from their probe
methods.

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

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

Add 32-bit support for Gxemul's oldtestmips machine emulation

Original work by: kan@

Mechanically substitute flags from historic mbuf allocator with
malloc(9) flags in sys/dev.

Use MIPS_PHYS_TO_DIRECT_UNCACHED rather than a homegrown version which is not
compatible with 32-bit kernels.

Correct an error in gxemul_disk_write(). It was issuing the command to
read from rather than write to the emulated disk.

Reviewed by: jmallett

In the gxemul console, check the RB_SERIAL boot flag, and change the
relative priority of the gxemul console in line with its role as a
"seiral console". This allows it to override video console drivers
that might otherwise take precdence, subject to that boot flag.

Sponsored by: DARPA, AFRL

Rename the gxemul console device to "ttyu0" to match the expectations of
the default MIPS /etc/ttys.

Sponsored by: DARPA, AFRL

Add a trivial driver for the GXemul Ethernet device. Probably quite buggy and
certainly non-optimal, but enough for basic networking use.

Requested by: rwatson

Add a driver for the GXemul test machine's disk controller and disk devices.
Prefer it to using an md device in the GXEMUL kernel configuration.

Requested by: rwatson, theraven

Merge a rudimentary gxemul "oldtestmips" port. This consists almost
entirely of one machdep file lifted from the MALTA port, as well as
a low-level console and tty driver for the gxemul debugging console
device (the emulators stdio). As with many low-level embedded and
hypervisor console devices, it is polled only, so we drive TTY I/O
from a callout; we are perhaps a bit too aware of the MIPS physical
maps in order to attach the console before newbus comes to life.

The sample kernel configuration depends on an MD-based root file
system, which is not provided. However, any 64-bit, big-endian
userspace image (such as one generated for MALTA) should work.

This will hopefully be supplemented by additional device drivers for
gxemul-specific hardware simulations from Juli Mallett. We have
found oldtestmips quite useful for testing and improving aspects of
the MIPS port, so it's worth supporting better in FreeBSD.

Requested by: theraven, jmallett
Sponsored by: DARPA, AFRL
MFC after: 3 weeks