Deprecate the mtab service script

The mtab service script is no longer needed on modern Linux systems, so
we can remove it in 1.0. However, we need to set a deprecation notice
first.

init.d/mtab.in

@@ -12,12 +12,16 @@ depend()
 
 start()
 {
-	if [ -L /etc/mtab ]
-	then
-		einfo "Skipping mtab update (mtab is a symbolic link)"
+	if [ -L /etc/mtab ]; then
 		return 0
 	fi
 
+	ewarn "Please run the following command as root on your system."
+	ewarn
+	ewarn "ln -snf /proc/self/mounts /etc/mtab"
+	ewarn
+	ewarn "The support for updating /etc/mtab as a file is"
+	ewarn "deprecated and will be removed in the future."
 	ebegin "Updating /etc/mtab"
 	if ! echo 2>/dev/null >/etc/mtab; then
 		ewend 1 "/etc/mtab is not updateable"