This commit implements two more features:
* min_accept_backoff configuration option
* retry accept() after some close() calls
See also https://github.com/darkk/redsocks/issues/19
Remove warnings in archs using LP64 by dealing with [s]size_t arguments.
There is a special length modifier 'z' that should precede integer
conversion specifier in format strings using [s]size_t arguments.