INT 21 - DOS 3+ - CREATE TEMPORARY FILE
        AH = 5Ah
        CX = file attribute (see AX=4301h)
        DS:DX -> ASCIZ path ending with a '\' + 13 zero bytes to receive the
                generated filename
Return: CF clear if successful
            AX = file handle opened for read/write in compatibility mode
            DS:DX pathname extended with generated name for temporary file
        CF set on error
            AX = error code (03h,04h,05h) (see AH=59h)
Notes:  creates a file with a unique name which must be explicitly deleted
        COMPAQ DOS 3.31 hangs if the pathname is at XXXXh:0000h; it apparently
          wraps around to the end of the segment
        under the FlashTek X-32 DOS extender, the path pointer is in DS:EDX
SeeAlso: AH=5Bh