fix tripple n typos in "running"/"domainname", also one missing n in comments.

Allow architectures to define a macro PROC_MACHINE_ARCH(P) and
PROC_MACHINE_ARCH32(P) to override the value for sysctl hw.machine_arch
(native and netbsd32 commpat resp.).

Use these for arm and mips instead of the (not working, noisy, in case
of arm) sysctl override and #ifdef __mips__ in architecture neutral
code.

Move a bunch of sysctl nodes from init_sysctl (kitchen sink sysctl file)
to init_sysctl_base (only base kernel defs). Main motivation was to
fix sysconf(_SC_NPROCESSORS) for Rumprun. As reported by neeraj on irc,
it returned -1 before this fix, so we were doing imaginary computing.

hw nodes do not go under the kern tree, so add new init routine for them

Missing includes for some architectures

Move hw.machine and hw.machine_arch sysctls to base so rump can use them

This allows uname(3) and uname(1) to work on rump kernels.

branches: 1.3.6;
Ensure that the top level sysctl nodes (kern, vfs, net, ...) exist before
the sysctl link sets are processed, and remove redundancy.

Shaves >13kB off of an amd64 GENERIC, not to mention >1k duplicate
lines of code.

Add kern.{ostype,osrelease,osrevision,version} kern.domainname,
kern.rawpartition sysctl support to rump kernel.
Moved the sysctl support that is shared between rump and normal
kernels to init_sysctl_base.c as rump cannot use init_sysctl.c
in order to avoid code duplication. Agreed with pooka@.

branches: 1.1.4; 1.1.14; 1.1.24; 1.1.28;
Chop init_sysctl into base nodes (init_sysctl_base.c) and the
kitchen sink (init_sysctl.c). Further surgery may be needed down
the line.