MFP4: 223121 (PIC portion), 225861, 227822, 229692 (PIC only), 229693,
230523, 1123614

Implement a driver for Robert Norton's PIC as an FDT interrupt
controller. Devices whose interrupt-parent property points to a beripic
device will have their interrupt allocation, activation , and setup
operations routed through the IC rather than down the traditional bus
hierarchy.

This driver largely abstracts the underlying CPU away allowing the
PIC to be implemented on CPU's other than BERI. Due to insufficient
abstractions a small amount of MIPS specific code is currently required
in fdt_mips.c and to implement counters.

MFC after:	3 days
Sponsored by:	DARPA/AFRL
Sync BERI kernel configs with P4:

Switch the majority of device configuration to FDT from hints.

Add BERI_*_BASE configs to reduce duplication in the MDROOT and SDROOT
kernels.

Add NFS and GSSAPI support by default.

MFC after:	3 days
Sponsored by:	DARPA/AFRL
Ignore registers on devices where the reg property is malformed. Issue a
warning if this happens under bootverbose. This prevents some
strange-looking entries in dmesg for SMU devices on Apple G5 systems.
Stop conflating WITHOUT_CLANG with WITHOUT_CLANG_IS_CC.  This allows
bootstrapping a copy of clang without building clang for the base system
which is useful for nanobsd and similar setups.  It's still probably
wrong to conflate what is installed as /usr/bin/cc with the selection
of a bootstrap compiler under WITH*_CLANG_IS_CC, but that's for another
day.

MFC after:	1 week
Sponsored by:	DARPA/AFRL