INT 31 - DPMI 0.9+ - SIMULATE REAL MODE INTERRUPT

	AX = 0300h
	BL = interrupt number
	BH = flags
	    bit 0: reset the interrupt controller and A20 line (DPMI 0.9)
		    reserved, must be 0 (DPMI 1.0+)
	    others: reserved, must be 0
	CX = number of words to copy from protected mode to real mode stack
	ES:(E)DI = selector:offset of real mode call structure (see #03148)
Return: CF clear if successful
	    real mode call structure modified (all fields except SS:SP, CS:IP
	      filled with return values from real mode interrupt)
	CF set on error
	    AX = error code (DPMI 1.0+) (8012h,8013h,8014h,8021h)(see #03143)
	protected mode stack unchanged
Notes:	16-bit programs use ES:DI as pointer, 32-bit programs use ES:EDI
	CS:IP in the real mode call structure is ignored for this call,
	  instead, the indicated interrupt vector is used for the address
	the flags in the call structure are pushed on the real mode stack to
	  form an interrupt stack frame, and the trace and interrupt flags are
	  clear on entry to the handler
	DPMI will provide a small (30 words) real mode stack if SS:SP is zero
	the real mode handler must return with the stack in the same state as
	  it was on being called
SeeAlso: AX=0302h,AX=FF01h,INT 21/AX=2511h,INT 21/AH=E3h"OS/286"
SeeAlso: INT 2C/AX=0026h,INT 2F/AX=FB42h/BX=000Dh