Bug#38692 concurrent inserts cause valgrind errors in Query_cache::invalidate

Concurrent inserts produce valgrind error messages.
The reason is that the query cache is invalidated after the target table object
is closed.

Since the delayed insert thread already takes care of invalidating the query
cache there is no need to try to synchronize an extra cache invalidation call.

The fix is to remove the query_cache_invalidate3 call altogether.

sql/sql_insert.cc

@@ -830,7 +830,6 @@ bool mysql_insert(THD *thd,TABLE_LIST *table_list,
       info.copied=values_list.elements;
       end_delayed_insert(thd);
     }
-    query_cache_invalidate3(thd, table_list, 1);
   }
   else
 #endif