i386.  Stop abusing it on other archs for controling a shutdown by
pressing the soft power button:
* Add a MI sysctl hw.allowpowerdown; if set to 1 (the default) it
allows a power button shutdown.
* Make acpi(4)/acpibtn(4) honor hw.allowpowerdown.
* Switch the various power button intercepts on landisk, sgi, sparc64
and zaurus over to hw.allowpowerdown.
* Garbage collect the machdep.kbdreset sysctl on all archs other than
amd64 and i386.
ok miod@

variables from arch/sh/ to arch/landisk/. ok deraadt@

up to machdep.kbdreset; modelled after the sparc64 power(4) driver
discussed with miod@ and jsg@

apmd(8); missing sysctl variable noticed by drahn@

is being renamed to macppc. This is to allow sharing of common code
between different powerpc base platforms.
Files moved from etc/etc.powerpc to etc/etc.macppc