INT 31 P - DPMIsee DOS Protected-Mode Interface 0.9+ - GET AND ENABLE VIRTUAL INTERRUPT STATE
	AX = 0901h
Return: CF clear
	virtual interrupts enabled
	AL = previous interrupt state (00h disabled, 01h enabled)
	AH preserved
Notes:	the previous state may be restored simply by executing another INT 31
	a STI instruction may be used if the previous state is unimportant,
	  but should be assumed to be very slow due to trapping by the host
SeeAlso: AX=0900h,AX=0902h