Put _rc_err argument under quotes to respect the syntax we are passing.

src/etc/rc.d/rc.subr

@@ -1,4 +1,4 @@
-#	$OpenBSD: rc.subr,v 1.87 2014/08/24 17:15:24 ajacoutot Exp $
+#	$OpenBSD: rc.subr,v 1.88 2014/08/25 07:34:12 ajacoutot Exp $
 #
 # Copyright (c) 2010, 2011, 2014 Antoine Jacoutot <ajacoutot@openbsd.org>
 # Copyright (c) 2010, 2011 Ingo Schwarze <schwarze@openbsd.org>
@@ -20,7 +20,7 @@
 # Default functions and variables used by rc.d(8) scripts.
 
 _rc_err() {
-	echo $1 1>&2
+	echo "$1" 1>&2
 	exit 1
 }