powerd to use sysctl to import temps to drop freq to avoid heat crash

[Ian Smith]

On Thu, 5 Jan 2012, Ian Smith wrote:
 > =======
 > #!/bin/sh
 > # temp_t23 smithi v0 7/11/11, tidy 12/11/11, v2 fan read delay 22/11/11

 + # Credit to Alexandre "Sunny" Kovalenko <gaijin.k at gmail.com> whose
 + # earlier scripts for managing acpi_ibm resources inspired this one.

 > # v3 18/12/11 suspend / resume resets dev.acpi_ibm.0.fan=1 (ie auto)
 > none=0; slow=1; fast=3	# Thinkpad T23 fan levels (1-2, 3-7 same)

And of course it was also Alexandre who (I think originally) proposed 
monitoring temperature to directly implement cooling via lower powerd 
freqs, according to old email, in Feb 2006.  I'd even forgotten having 
reviewed and added a line or two to that patch .. if I lost my archives 
I'd probably have no memory left at all :)

This post:
 http://lists.freebsd.org/pipermail/freebsd-acpi/2008-February/004521.html
points to this PR:
 http://www.freebsd.org/cgi/query-pr.cgi?pr=bin%2F120336&cat=
which was closed with reference to this post:
 http://docs.FreeBSD.org/cgi/mid.cgi?1203126071.833.19.camel

Useless trying to apply anything like this to recent powerd sources, 
though.  Good luck with getting its fan to go, or a warranty claim!

cheers, Ian