INT E0 - REAL/32 - "DEV_TWAITFLAG" - TIMED WAIT ON SYSTEM FLAG

	CL = B7h
	DS:DX -> Flag Parameter Block (FPB) (see #04058)
Return: AX = status
	may destroy SI,DI,DS
Note:	if the flag was already set, this function returns immediately
SeeAlso: INT E0/CL=84h,INT E0/CL=85h