Fixed compiler warnings.

sql/item.cc

@@ -8866,7 +8866,7 @@ inline struct st_select_lex *Item_ident::get_depended_from() const
 {
   st_select_lex *dep;
   if ((dep= depended_from))
-    for ( ; dep->merged_into; dep= dep->merged_into);
+    for ( ; dep->merged_into; dep= dep->merged_into) ;
   return dep;
 }
 

sql/sql_derived.cc

@@ -857,14 +857,13 @@ bool mysql_derived_create(THD *thd, LEX *lex, TABLE_LIST *derived)
 
 bool mysql_derived_fill(THD *thd, LEX *lex, TABLE_LIST *derived)
 {
-  TABLE *table= derived->table;
   SELECT_LEX_UNIT *unit= derived->get_unit();
   bool res= FALSE;
 
   if (unit->executed && !unit->uncacheable && !unit->describe)
     return FALSE;
   /*check that table creation passed without problems. */
-  DBUG_ASSERT(table && table->created);
+  DBUG_ASSERT(derived->table && derived->table->created);
   SELECT_LEX *first_select= unit->first_select();
   select_union *derived_result= derived->derived_result;
   SELECT_LEX *save_current_select= lex->current_select;

sql/sql_select.cc

@@ -12091,7 +12091,7 @@ Field *create_tmp_field(THD *thd, TABLE *table,Item *item, Item::Type type,
          (orig_item && orig_item->maybe_null)) && /* for outer joined views/dt*/        
         !field->field->maybe_null())
     {
-      bool save_maybe_null;
+      bool save_maybe_null= FALSE;
       /*
         The item the ref points to may have maybe_null flag set while
         the ref doesn't have it. This may happen for outer fields