build/base: symlink dbus only in /run/dbus

In previous patches, we symblinked all /run to /var/run but it broke
some services like cloud-init: some symlinks were using relative paths
in /run and because of the symlink to /var/run, cloud-init was broken
(maybe and for sure other services thinkin they are in /run).

[root@os-ci-test4 ~]# ls -al /run/cloud-init/
total 0
drwxr-xr-x  2 root root  60 Aug 21 06:47 .
drwxr-xr-x 24 root root 720 Aug 21 06:47 ..
lrwxrwxrwx  1 root root  36 Aug 21 06:47 status.json ->
../../var/lib/cloud/data/status.json
[root@os-ci-test4 ~]# ls -al /var/run/cloud-init/
total 0
drwxr-xr-x  2 root root  60 Aug 21 06:47 .
drwxr-xr-x 24 root root 720 Aug 21 06:47 ..
lrwxrwxrwx  1 root root  36 Aug 21 06:47 status.json ->
../../var/lib/cloud/data/status.json

This patch create a symlink from /var/run/dbus/system_bus_socket to
/run/dbus/ because it's today the only one issue we had in the
deployment of RHEL7.

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>

Author: Emilien Macchi

build/base.install

@@ -334,10 +334,10 @@ systemd_fix() {
     case "$dist" in
         $supported_centos_dists|$supported_redhat_dists)
             if [ $CODENAME_MAJOR = 7 ]; then
-                if [ -d $target/run ]; then
-                    rm -rf $target/run
+                if [ -d $target/run/dbus ]; then
+                    rm -rf $target/run/dbus
                 fi
-                do_chroot $target ln -sf /var/run /
+                do_chroot $target ln -sf /var/run/dbus/system_bus_socket /run/dbus/
             fi
         ;;
     esac