MDEV-19457: sys_vars.wsrep_provider_basic failed in buildbot

If the initialization of the wsrep provider failed, in some
cases the internal variable wrep_inited indicating that the
initialization has already been completed is still set to
"1", which then leads to confusion in the initialization
status. To solve the problem, we should set this variable
to "1" only if the wsrep provider initialization really
completed successfully.

An earlier issue has already been fixed for branch 10.4,
and this patch contains a fix for earlier versions (where
Galera 3.x is used).

sql/wsrep_mysqld.cc

@@ -599,7 +599,6 @@ int wsrep_init()
   {
     // enable normal operation in case no provider is specified
     wsrep_ready_set(TRUE);
-    wsrep_inited= 1;
     global_system_variables.wsrep_on = 0;
     wsrep_init_args args;
     args.logger_cb = wsrep_log_cb;
@@ -610,10 +609,15 @@ int wsrep_init()
     {
       DBUG_PRINT("wsrep",("wsrep::init() failed: %d", rcode));
       WSREP_ERROR("wsrep::init() failed: %d, must shutdown", rcode);
+      wsrep_ready_set(FALSE);
       wsrep->free(wsrep);
       free(wsrep);
       wsrep = NULL;
     }
+    else
+    {
+      wsrep_inited= 1;
+    }
     return rcode;
   }
   else