Make fancontrol safer on kernel panic

[khali]

It was reported that hardware could be damaged on kernel panic when fancontrol is in use. If the fan speed happens to be low at the time of panic, there is a risk that the system overheats by the time the administrator restarts the system.

Possible solutions include:

• Writing a non-zero value to /proc/sys/kernel/panic when fancontrol starts and restoring the original value when leaving. $INTERVAL would seem to be an appropriate value to write.
• Updating the documentation to recommend the use of a watchdog on any system doing software-based fan speed control.