More merge fixes:

- mdl.cc and mdl.h merged completely
- mysql_system_tables*.sql merged completely
- Fixed wrong merge of lock_tables
- Added some missing functions:
 - bool THD::notify_shared_lock()
 - Dynamic_array::pop, Dynamic_array::del
- Added MDL_context_owner to THD
- Added metadata_locks_hash_instances

sql/sql_class.cc

@@ -62,6 +62,7 @@
 #include "debug_sync.h"
 #include "sql_parse.h"                          // is_update_query
 #include "sql_callback.h"
+#include "lock.h"
 #include "sql_connect.h"
 
 /*
@@ -1788,6 +1789,46 @@ void THD::disconnect()
 }
 
 
+bool THD::notify_shared_lock(MDL_context_owner *ctx_in_use,
+                             bool needs_thr_lock_abort)
+{
+  THD *in_use= ctx_in_use->get_thd();
+  bool signalled= FALSE;
+
+  if ((in_use->system_thread & SYSTEM_THREAD_DELAYED_INSERT) &&
+      !in_use->killed)
+  {
+    in_use->killed= KILL_CONNECTION;
+    mysql_mutex_lock(&in_use->mysys_var->mutex);
+    if (in_use->mysys_var->current_cond)
+      mysql_cond_broadcast(in_use->mysys_var->current_cond);
+    mysql_mutex_unlock(&in_use->mysys_var->mutex);
+    signalled= TRUE;
+  }
+
+  if (needs_thr_lock_abort)
+  {
+    mysql_mutex_lock(&in_use->LOCK_thd_data);
+    for (TABLE *thd_table= in_use->open_tables;
+         thd_table ;
+         thd_table= thd_table->next)
+    {
+      /*
+        Check for TABLE::needs_reopen() is needed since in some places we call
+        handler::close() for table instance (and set TABLE::db_stat to 0)
+        and do not remove such instances from the THD::open_tables
+        for some time, during which other thread can see those instances
+        (e.g. see partitioning code).
+      */
+      if (!thd_table->needs_reopen())
+        signalled|= mysql_lock_abort_for_thread(this, thd_table);
+    }
+    mysql_mutex_unlock(&in_use->LOCK_thd_data);
+  }
+  return signalled;
+}
+
+
 /*
   Get error number for killed state
   Note that the error message can't have any parameters.