experimental/tsak

This is an experimental SAK filter that uses evdev and friends to:
1.) Signal when a SAK (currently hardcoded as Ctrl+Alt+DEL) is pressed
    This signal is ONLY available to applications running as root
2.) Filter any SAK press events out, so that no non-root applications are aware of them if they occur.
    In fact, even root applications will be unaware of the SAK press unless they are monitoring
    the out-of-band SAK interface.

The interface is very simple.  Listen on /tmp/ksocket-global/tsak and you will receive the null-terminated string "SAK\n\r" when the SAK is pressed.
Note that the string may be sent multiple times, especially if the SAK is held down.