We generate a corresponding constant (in lower case) in paths.ml. Use
that in source code to get rid of hard-coded path.
Note that with this patch the default location for xenstored*.log is
changed from /var/log to /var/log/xen.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: David Scott <dave@recoil.org>