INT 2F - MS WINDOWS - "VMD" VIRTUAL DEVICE API
        AX = 1607h
        BX = 000Ch (VxD identifier of "VMD")
Return: CX = nonzero if mouse driver already virtualized
Note:   VMD (Virtual Mouse Driver) calls this and then checks whether CX is
          nonzero; if yes, it will not automatically virtualize the mouse
          driver.  This would be used if MOUSE.COM already virtualizes
          itself using the Windows API.
SeeAlso: AX=1607h/BX=0015h