BUG/MINOR: queue: properly report redistributed connections

BUG/MINOR: queue: properly report redistributed connections

In commit 5cd4bbd7a ("BUG/MAJOR: threads/queue: Fix thread-safety issues
on the queues management") the counter of transferred connections was
accidently lost, so that when a server goes down with connections in its
queue, it will always be reported that 0 connection were transferred.

This should be backported as far as 1.8 since the patch above was
backported there.

(cherry picked from commit ef71f0194cfdaa9c201bece65e8c1ab3d16ed8a0)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit e6985c91c3dd1100950987a5bf98eaeb863c97b8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>