http: get_addr: return sockaddr pointer instead of sockaddr_storage.

As Nick pointed:
https://github.com/azat/libevent/commit/a7a14f0b65bcdb7f89a6418625b5fac8f7de3a0e#commitcomment-4302514

The platform is not guaranteed to have struct sockaddr_storage.
test: regress_http: use sockaddr instead of sockaddr_storage.