MWL#17: Table elimination

- Fix trivial valgrind failures that shown up after review

sql/opt_table_elimination.cc

@@ -40,7 +40,7 @@
   Table elimination is redone on every PS re-execution.
 */
 
-class Value_dep
+class Value_dep : public Sql_alloc
 {
 public:
   enum {
@@ -48,6 +48,9 @@ public:
     VALUE_TABLE,
   } type; /* Type of the object */
   
+  Value_dep(): bound(FALSE), next(NULL)
+  {}
+
   bool bound;
   Value_dep *next;
 };