Emit "no servers could be reached" for TCP as well as UDP

When all the servers are exhausted for TCP emit "no servers could
be reached" in tcp_connected.  This message is already emitted for
UDP.

(cherry picked from commit 831efa40d6)

bin/dig/dighost.c

@@ -3654,6 +3654,7 @@ tcp_connected(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
 			start_tcp(next);
 			check_if_done();
 		} else {
+			dighost_error("no servers could be reached\n");
 			clear_current_lookup();
 		}