Fixed handling of unix sockets in $binary_remote_addr. Previously, unix sockets were treated as AF_INET ones, and this may result in buffer overread on Linux, where unbound unix sockets have 2-byte addresses. Note that it is not correct to use just sun_path as a binary representation for unix sockets. This will result in an empty string for unbound unix sockets, and thus behaviour of limit_req and limit_conn will change when switching from $remote_addr to $binary_remote_addr. As such, normal text representation is used. Reported by Stephan Dollberg.