Bug#38560: valgrind warnings on PB due to query profiling

Fix for a valgrind warning due to a jump on a uninitialized
variable. The problem was that the sql profile preparation
function wasn't being called for all possible code paths
of query execution.

The solution is to ensure that query profiling is always
started before dispatch_command function is called and to
explicitly call the profile preparation function on bootstrap.

sql/sql_parse.cc

@@ -329,6 +329,12 @@ void execute_init_command(THD *thd, sys_var_str *init_command_var,
   Vio* save_vio;
   ulong save_client_capabilities;
 
+#if defined(ENABLED_PROFILING) && defined(COMMUNITY_SERVER)
+  thd->profiling.start_new_query();
+  thd->profiling.set_query_source(init_command_var->value,
+                                  init_command_var->value_length);
+#endif
+
   thd_proc_info(thd, "Execution of init_command");
   /*
     We need to lock init_command_var because
@@ -350,6 +356,10 @@ void execute_init_command(THD *thd, sys_var_str *init_command_var,
   rw_unlock(var_mutex);
   thd->client_capabilities= save_client_capabilities;
   thd->net.vio= save_vio;
+
+#if defined(ENABLED_PROFILING) && defined(COMMUNITY_SERVER)
+  thd->profiling.finish_current_query();
+#endif
 }
 
 
@@ -441,6 +451,7 @@ pthread_handler_t handle_bootstrap(void *arg)
     thd->query[length] = '\0';
     DBUG_PRINT("query",("%-.4096s",thd->query));
 #if defined(ENABLED_PROFILING) && defined(COMMUNITY_SERVER)
+    thd->profiling.start_new_query();
     thd->profiling.set_query_source(thd->query, length);
 #endif
 
@@ -456,6 +467,10 @@ pthread_handler_t handle_bootstrap(void *arg)
     bootstrap_error= thd->is_error();
     net_end_statement(thd);
 
+#if defined(ENABLED_PROFILING) && defined(COMMUNITY_SERVER)
+    thd->profiling.finish_current_query();
+#endif
+
     if (bootstrap_error)
       break;