migration/colo.c: Relaunch failover even if there was an error

migration/colo.c: Relaunch failover even if there was an error

If vmstate_loading is true, secondary_vm_do_failover will set failover
status to FAILOVER_STATUS_RELAUNCH and return success without initiating
failover. However, if there is an error during the vmstate_loading
section, failover isn't relaunched. Instead we then wait for
failover on colo_incoming_sem.

Fix this by relaunching failover even if there was an error. Also,
to make this work properly, set vmstate_loading to false when
returning during the vmstate_loading section.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Message-Id: <f60b0a8e2fadaaec792e04819dfc46951842d6ba.1589193382.git.lukasstraub2@web.de>
Reviewed-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>