void freecli(cli_s *cli);
frees all ezcli-owned piece of memory which are the
cli_s struct and options initialized using
allocopt().
see ezcli/cli_s for explanation of what
cli_s is.
see ezcli/allocopt for explanation of what
allocopt() does.
freecli() is also run when ezcli comes across a syntax
error and has to exit.