Core Update 167: Replace /etc/mtab by symlink to /proc/self/mounts

mount, as updated via util-linux, no longer writes /etc/mtab, causing
programs to rely on this file's content (such as the check_disk Nagios
plugin) to stop working.

/proc/self/mounts contains all the necessary information, so it is fine
to replace /etc/mtab by a symlink to it.

Fixes: #12843

Signed-off-by: Peter Müller <peter.mueller@ipfire.org>

config/rootfiles/core/167/filelists/files

@@ -1,7 +1,9 @@
 etc/collectd.conf
 etc/inittab.d
 etc/rc.d/init.d/firewall
+etc/rc.d/init.d/mountfs
 etc/rc.d/init.d/pakfire
+etc/rc.d/init.d/partresize
 etc/sysctl.conf
 lib/udev/network-hotplug-bridges
 srv/web/ipfire/cgi-bin/connections.cgi

config/rootfiles/core/167/update.sh

@@ -386,6 +386,10 @@ hardlink -c -vv /lib/firmware
 # Regenerate all initrds
 dracut --regenerate-all --force
 
+# Replace /etc/mtab by symlink as mount no longer writes it
+rm -vf /etc/mtab
+ln -vs /proc/self/mounts /etc/mtab
+
 # Export the location database again and reload the firewall engine
 /usr/local/bin/update-location-database