INT 31 P - DPMI 1.0+ - FREE SERIALIZATION ON SHARED MEMORY
        AX = 0D03h
        SI:DI = shared memory block handle
        DX = flags
            bit 0: release shared serialization rather than exclusive serialztn
            bit 1: free pending serialization
            bits 2-15: reserved (0)
Return: CF clear if successful
        CF set on error
            AX = error code (8002h,8023h) (see AX=0000h)
SeeAlso: AX=0D02h