Compatibility:  WIN 3.0+
Expects: AX    1702H
                                                                  
Returns: AX    0000h = fn failed
else  = fn completed successfully
                                                                  
Info: Discards the current contents of the Windows clipboard and frees
up any memory used to hold that data.  Equivalent to
EmptyClipboard.

The clipboard must be open.  See INT 2fH 1701H.

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INT 2fH 1702H: Discard Clipboard Contents