MINOR: http/htx: use conn_get_dst() to retrieve the destination address

When adding the X-Original-To header, let's use conn_get_dst() and make
sure it succeeds, since  previous call to conn_get_to_addr() was unchecked.
diff --git a/src/http_ana.c b/src/http_ana.c
index ac3412b..2009180 100644
--- a/src/http_ana.c
+++ b/src/http_ana.c
@@ -864,12 +864,10 @@
 	if ((sess->fe->options | s->be->options) & PR_O_ORGTO) {
 
 		/* FIXME: don't know if IPv6 can handle that case too. */
-		if (cli_conn && cli_conn->addr.from.ss_family == AF_INET) {
+		if (cli_conn && cli_conn->addr.from.ss_family == AF_INET && conn_get_dst(cli_conn)) {
 			/* Add an X-Original-To header unless the destination IP is
 			 * in the 'except' network range.
 			 */
-			conn_get_to_addr(cli_conn);
-
 			if (cli_conn->addr.to.ss_family == AF_INET &&
 			    ((!sess->fe->except_mask_to.s_addr ||
 			      (((struct sockaddr_in *)&cli_conn->addr.to)->sin_addr.s_addr & sess->fe->except_mask_to.s_addr)