INT 2C P - RM386 v6.00 - CLOAKING - CALL V86-MODE INTERRUPT HANDLER
        AX = 0026h
        DS:EBX -> client register structure (see AX=0009h)
        CX = interrupt number
Return: CF clear if successful
            client register structure updated
        CF set if no more nested procedure call space available
Note:   this call uses the V86-mode stack supplied in the client structure
SeeAlso: AX=0025h,AX=0027h,INT 31/AX=0300h

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