tools/xenstore: start with empty data base

tools/xenstore: start with empty data base

Today xenstored tries to open a tdb data base file on disk when it is
started. As this is problematic in most cases the scripts used to start
xenstored ensure xenstored won't find such a file in order to start
with an empty xenstore.

A tdb data base file can't be used to restore all Xenstore state as
e.g. Xenstore watches are not kept in the tdb data base. The file is
meant to be used for debugging purposes after a xenstored crash only.

Instead of opening a Xenstore data base file found on disk always start
with an empty data base. This will avoid problems in case someone is
testing multiple xenstored versions without rebooting (which is not
supported but helps debugging in some cases).

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>