I think it was part of one of the BB updates? Or maybe it was in 3.9 initially. It's only like 64 bytes, I can send it to you if you need it. I really don't like flipping that power switch any more than necessary, our Miggy's aren't getting any younger! 
I came up with 64 bytes also assembling the following with vasm.
move.l (4).w,a6
JSRLIB ColdReboot
This is not a hard reboot like turning off the machine. Sometimes there is a difference if the system has been badly corrupted or there has been something reboot proof added. The 3 finger salute can be held for several seconds until the screen changes shades. This usually saves turning the Amiga off but I have seen a few times when this doesn't even work for a hard reboot (usually with a red screen).
