root.sh: Make sure we have all package metadata

Run `apt-get update` after the installation so we fetch all
the meta data for e.g. GNOME Software. This makes a better
first impression when firering this up.

Suggested by Matthias Klumpp

root.sh

@@ -153,6 +153,8 @@ function check_patched()
 function cleanup_chroot()
 {
     chroot "${basedir}" apt-get clean
+    # Make sure we have DEP11 info
+    chroot "${basedir}" apt-get update
 
     rm "${basedir}/etc/resolv.conf"
     mv "${basedir}/etc/resolv.conf.bak" "${basedir}/etc/resolv.conf"