Bugfix: The socket id is not the same descriptor for reading.

Bugfix: The socket id is not the same descriptor for reading.

When binding and listening on some socket id, the accept call on that socket creates a new descriptor.
That descriptor is not the same as the original socket id.

Add a new id_data to the socket structure to represent the data transfer file descriptor that is created via the accept() call.
Add a new f_file_close_id() to close the file by the id in case the f_file_t is not available or in use.