Compatibility:  WIN 3.0+
Expects: AX    1701H
                                                                  
Returns: AX    0000h = clipboard already open (fn failed)
else  = opened successfully
                                                                  
Info: You must use this fn before any other clipboard fns.  It enables
INT 2fH access to the clipboard by giving ownership to the window
displayed by the WinOldApp program.  Equivalent to OpenClipboard.

Be sure to use INT 2fH 1708H (close clipboard) when finished
accessing the clipboard.

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INT 2fH 1701H: Get Access to Clipboard