spec: initialize default kernel when creating qubes.xml database

This is especially important when kernel-qubes-vm's %post was executed
before qubes-core-dom0's %post - in that case, the default kernel would
be left as "None".

rpm_spec/core-dom0.spec

@@ -220,6 +220,7 @@ service xenstored start
 if ! [ -e /var/lib/qubes/qubes.xml ]; then
 #    echo "Initializing Qubes DB..."
     umask 007; sg qubes -c qvm-init-storage
+    qubes-prefs -s default-kernel `ls /var/lib/qubes/vm-kernels|head -n 1` 2> /dev/null
 fi
 
 # Because we now have an installer