Ensure that spurious results from system's getaddrinfo() ares not propagated
by Curl_getaddrinfo_ex() into the library.
Also ensure that the ai_addrlen member of Curl_getaddrinfo_ex()'s output linked
list of Curl_addrinfo structures has appropriate family-specific address size.
CURLOPT_RESOLVE is a new option that sends along a curl_slist with
name:port:address sets that will populate the DNS cache with entries so
that request can be "fooled" to use another host than what otherwise
would've been used. Previously we've encouraged the use of Host: for
that when dealing with HTTP, but this new feature has the added bonus
that it allows the name from the URL to be used for TLS SNI and server
certificate name checks as well.
This is a first change. Surely more will follow to make it decent.
Previous workaround proved useful, but triggered the following warning:
warning #556: a value of type "volatile Curl_addrinfo *" cannot be assigned to an entity of type "Curl_addrinfo *"
Previous 'volatile' variables workaround proved useful, but it triggered the following warning:
warning #167: argument of type "volatile Curl_addrinfo *" is incompatible with parameter of type "void *"
