Add Statement::sql_command_flags() function.

Now one can call thd->sql_command_flags() instead of
sql_command_flags[thd->lex->sql_command].

sql/sql_class.h

@@ -1489,6 +1489,8 @@ struct send_column_info_state
   }
 };
 
+extern uint sql_command_flags[];
+
 
 /**
   @class Statement
@@ -1569,6 +1571,10 @@ public:
   {
     set_query_inner(CSET_STRING());
   }
+  ulong sql_command_flags() const
+  {
+    return ::sql_command_flags[lex->sql_command];
+  }
   /**
     Name of the current (default) database.