For a long time (since 7.28.1) we've returned error when setting the
value to 1 to make applications notice that we stopped supported the old
behavior for 1. Starting now, we treat 1 and 2 exactly the same.
Closes#4241
In DarwinSSL the SSLSetPeerDomainName function is used to enable both
sending SNI and verifying the host. When host verification is disabled
the function cannot be called, therefore SNI is disabled as well.
Closes https://github.com/curl/curl/pull/1240
