NOMMU re-exec trick shuld not depend on existence of "don't daemonize"

option for every affected applet (and dnsd, for example, don't have one).
Thus rework re-exec support to not require it. Code got smaller too.

networking/dnsd.c

@@ -357,8 +357,8 @@ int dnsd_main(int argc, char **argv)
 	if (OPT_daemon) {
 //FIXME: NOMMU will NOT set LOGMODE_SYSLOG!
 #ifdef BB_NOMMU
-		/* reexec for vfork() do continue parent */
-		vfork_daemon_rexec(1, 0, argc, argv, "-d");
+		if (!re_execed)
+			vfork_daemon_rexec(1, 0, argv);
 #else
 		xdaemon(1, 0);
 #endif