TIdSocketList - List of duplicated socket handles.

Clone is an overridden TIdSocketList function that implements the interface used to create a duplicate copy of the socket descriptors stored in the list. 

Clone calls Lock to protect resource in the current socket list prior to cloning the socket descriptors, and calls Unlock to free the resource protection used during the operation. 

The return value for the method is a new TIdSocketListWindows instance created for the cloned socket handles. 

Clone calls SetFDSet to store a copy of the current set of socket descriptors in the socket list.