MINOR: connection: use sni as parameter for srv conn hash

The sni parameter is an input to the server connection hash. Do not add
anymore connections with dynamic sni in the private list. Thus, it is
now possible to reuse a server connection if they use the same sni.
diff --git a/src/connection.c b/src/connection.c
index 3656b36..6126dd1 100644
--- a/src/connection.c
+++ b/src/connection.c
@@ -1423,6 +1423,12 @@
 
 	conn_hash_update(buf, &idx, &params->srv, sizeof(params->srv), &hash_flags, 0);
 
+	if (params->sni_prehash) {
+		conn_hash_update(buf, &idx,
+		                 params->sni_prehash, sizeof(*params->sni_prehash),
+		                 &hash_flags, CONN_HASH_PARAMS_TYPE_SNI);
+	}
+
 	hash = conn_hash_digest(buf, idx, hash_flags);
 	return hash;
 }