Bug#19143857 GET RID OF DYNAMIC_ARRAY IN RPL_FILTER

Post-push fix
gcc 4.4.6 with -Werror -O3 said:
prealloced_array.h:226: error: 'job_worker.st_slave_job_group::ts' may be used uninitialized in this function

when we did push_back on an uninitialized object.
Fix: use value-initialization on the job_worker object.

Also fix some warnings from gcc 4.7.2 in optimized mode.

Author: Tor Didriksen

sql/rpl_mts_submode.cc

@@ -553,7 +553,7 @@ Mts_submode_logical_clock::get_least_occupied_worker(Relay_log_info *rli,
 {
   Slave_committed_queue *gaq= rli->gaq;
   Slave_worker *worker= NULL;
-  Slave_job_group* ptr_group;
+  Slave_job_group* ptr_group __attribute__((unused));
   PSI_stage_info *old_stage= 0;
   THD* thd= rli->info_thd;
   DBUG_ENTER("Mts_submode_logical_clock::get_least_occupied_worker");

sql/rpl_slave.cc

@@ -4843,7 +4843,10 @@ int mts_recovery_groups(Relay_log_info *rli)
   bool flag_group_seen_begin= FALSE;
   uint recovery_group_cnt= 0;
   bool not_reached_commit= true;
-  Slave_job_group job_worker;
+
+  // Value-initialization, to avoid compiler warnings on push_back.
+  Slave_job_group job_worker= Slave_job_group();
+
   IO_CACHE log;
   File file;
   LOG_INFO linfo;

sql/sql_plugin.cc

@@ -1063,7 +1063,7 @@ static void intern_plugin_unlock(LEX *lex, plugin_ref plugin)
       could be unlocked faster - optimizing for LIFO semantics.
     */
     plugin_ref *iter= lex->plugins.end() - 1;
-    bool found_it= false;
+    bool found_it __attribute__((unused)) = false;
     for (; iter >= lex->plugins.begin() - 1; --iter)
     {
       if (plugin == *iter)