Fix potential segmentation fault on iOS.

Fix potential segmentation fault on iOS.

The PONG handler could call freeaddrinfo() on a struct that was not
allocated with getaddrinfo(). On most platforms this apparently works
fine, but on iOS it will try to free memory that wasn't allocated. Fix
this by moving the code to reset an outgoing_t to a separate function,
and calling that from the PONG handler.