address family not set in example

[ghazel]

Here: https://github.com/nmathewson/libevent-book/blob/master/Ref6_bufferevent.txt#L271

The sockaddr_in is memset and the sin_addr and sin_port are set, but sin_family is not, leading to error 47 (Address family not supported by protocol family).

[errzey]

Good find. Since UNSPEC (0) is used, I'm fairly sure it was to show you could use any family; but in the example it is explicitly using ipv4 type settings. Patch here: #7

[nmathewson]

merged patch from ellzey; thanks all!