res_http_websocket.c: Set hostname on client for certificate validation.

Additionally add a `assert()` to in the TLS client setup code to
ensure that hostname is set when it is supposed to be.

Fixes #433

res/res_http_websocket.c

@@ -1162,6 +1162,12 @@ static struct ast_tcptls_session_args *websocket_client_args_create(
 	}
 	ast_sockaddr_copy(&args->remote_address, addr);
 	ast_free(addr);
+
+	/* We need to save off the hostname but it may contain a port spec */
+	snprintf(args->hostname, sizeof(args->hostname),
+		"%.*s",
+		(int) strcspn(host, ":"), host);
+
 	return args;
 }