Fix somewhat bogus GCC warning. Although needless as the base

class is mostly empty, initialize the base class explicitly in
the copy constructor.

sql/sql_list.h

@@ -74,7 +74,7 @@ public:
 
   SQL_I_List() { empty(); }
 
-  SQL_I_List(const SQL_I_List &tmp)
+  SQL_I_List(const SQL_I_List &tmp) : Sql_alloc()
   {
     elements= tmp.elements;
     first= tmp.first;