bridge: Complete initial configuration even with empty database.

bridge: Complete initial configuration even with empty database.

If the database was empty, that is, it did not even contain an Open_vSwitch
top-level configuration record, at ovs-vswitchd startup time, then
OVS failed to detach and used 100% CPU.  This commit fixes the problem.

This problem was introduced by commit 63ff04e82623e765 (bridge: Only
complete daemonization after db commits initial config.).

This problem did not manifest if the initscripts supplied with Open vSwitch
were used, because those initscripts always initialize the database before
starting ovs-vswitchd, so this problem affects only users with hand-rolled
local OVS startup scripts.

Bug #16090.
Reported-by: Pravin Shelar <pshelar@nicira.com>
Tested-by: Pravin Shelar <pshelar@nicira.com>
Reported-by: Paul Ingram <paul@nicira.com>
Reported-by: Amre Shakimov <ashakimov@vmware.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ansis Atteka <aatteka@nicira.com>