Comment 22 for bug 1208493

Merged the fix to release LOCK_global_system_variables when calling wsrep_stop_replication, also into wsrep-5.6.
It turned out, with new regression test, that 5.6 version is also vulnerable.
Note that wsrep_stop_replication is called both when wsrep_provider or wsrep_cluster_address is changed, so had to do the mutex release in both variable update handlers.

Fix in wsrep-5.6 is in revision: http://bazaar.launchpad.net/~codership/codership-mysql/5.6/revision/4031

wsrep-5.5 does not have protection in wsrep_cluster_address variable's update handler. So this poart of fix needs to merged in wsrep-5.5 as well.