thr_create_utime is uninitialised at this point. All 4 calls

to wsrep_init_thd_for_schema occur after a new THD so
it requires to initialize create time.

Author: janlindstrom

sql/wsrep_schema.cc

@@ -719,11 +719,8 @@ static void wsrep_init_thd_for_schema(THD *thd)
 {
   thd->security_ctx->skip_grants();
   thd->system_thread= SYSTEM_THREAD_GENERIC;
-
   thd->real_id=pthread_self(); // Keep purify happy
-
-  thd->prior_thr_create_utime= thd->start_utime= thd->thr_create_utime;
-
+  thd->prior_thr_create_utime= thd->start_utime= microsecond_interval_timer();
   /* No Galera replication */
   thd->variables.wsrep_on= 0;
   /* No binlogging */