INT 2F CU - NETWORK REDIRECTOR - RENAME REMOTE FILE
        AX = 1111h
        SS = DS = DOS DS
        SDA first filename pointer = offset of fully-qualified old name
        SDA second filename pointer = offset of fully-qualified new name
        SDA CDS pointer -> current directory structure for drive with file
Return: CF set on error
            AX = DOS error code (see INT 21/AH=59h)
        CF clear if successful
Note:   this function is called by the DOS 3.1+ kernel
SeeAlso: AX=1112h,INT 21/AH=56h,INT 21/AH=60h

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