Compatibility: Win 3.x
Expect: AX    1609H
Return: none
Info: TSRs and DOS-level device drivers may intercept this function as
a way to be notified when Windows is terminating.  It lets you
prepare to return to operating in a non-Windows environment.

Windows calls this at the start of a Sys_VM_Terminate device
control call.  All devices still exist at the time of this call,
so you can still call device entry-point addresses, if necessary.

- -

INT 2fH 1609H: Windows is Terminating