splx: Restore interrupts before dosoftints() for __HAVE_FAST_SOFTINTS.

No functional changes; All the users of arm32/spl.S, i.e., acorn32,
hpcarm/sa11x0, and shark have not switched to __HAVE_FAST_SOFTINTS yet.

Don't use cpsr_all/spsr_all with mrs, it doesn't take a mask.

Move parts of cpu.h that are not needed by MI code in <arm/locore.h>
Don't include <machine/cpu.h> or <machine/frame.h>, use <arm/locore.h>
Use <arm/asm.h> instead of <machine/arm.h>

branches: 1.8.18; 1.8.34; 1.8.44; 1.8.50;
Merge kernel changes in matt-armv6 to HEAD.

branches: 1.7.14; 1.7.16; 1.7.18;
Interrupt handling changes, in discussion since February:

- Reduce available SPL levels for hardware devices to none, vm, sched, high.
- Acquire kernel_lock only for interrupts at IPL_VM.
- Implement threaded soft interrupts.

branches: 1.6.2;
Merge the ppcoea-renovation branch to HEAD.

This branch was a major cleanup and rototill of many of the various OEA
cpu based PPC ports that focused on sharing as much code as possible
between the various ports to eliminate near-identical copies of files in
every tree. Additionally there is a new PIC system that unifies the
interface to interrupt code for all different OEA ppc arches. The work
for this branch was done by a variety of people, too long to list here.

TODO:
bebox still needs work to complete the transition to -renovation.
ofppc still needs a bunch of work, which I will be looking at.
ev64260 still needs to be renovated
amigappc was not attempted.

NOTES:
pmppc was removed as an arch, and moved to a evbppc target.

branches: 1.5.2;
Remove all references to spl_mask. Now it isn't used by any sources.
Discussed on port-arm.

branches: 1.4.24; 1.4.66; 1.4.74; 1.4.80; 1.4.82; 1.4.84; 1.4.86;
More local label fixups.

branches: 1.3.8;
Use <arm/arm32/psl.h>, not <machine/psl.h>.

branches: 1.2.4;
Tweak spl functions a little, try to do something between an ldr and it's use. Not the greatest of gains but spl is called a lot it might add up.
Also add comments stating alignment of stack.

branches: 1.1.2; 1.1.4;
Move the generic arm32 files into arm/arm32 from arm32/arm32, tested kernel builds on cats and riscpc.