gcc 4.0: Add some virtual destructors to make gcc 4.0 happy.

src/base/stats/output.hh

@@ -46,6 +46,7 @@ class FormulaInfo;
 
 struct Output
 {
+    virtual ~Output() {}
     virtual void begin() = 0;
     virtual void end() = 0;
     virtual bool valid() const = 0;

src/cpu/inorder/resource_pool.hh

@@ -122,7 +122,7 @@ class ResourcePool {
 
   public:
     ResourcePool(InOrderCPU *_cpu, ThePipeline::Params *params);
-    ~ResourcePool();    
+    virtual ~ResourcePool();
 
     std::string name();