Store various PID files under XEN_RUN_DIR. Note that this change the
default location from /var/run to /var/run/xen.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>