remove unused field

Author: bobzhang

src/dyndep.cc

@@ -57,9 +57,7 @@ bool DyndepLoader::LoadDyndeps(Node* node, DyndepFile* ddf,
               "'" + node->path() + "'");
       return false;
 #endif      
-    }
-
-    ddi->second.used_ = true;
+    }    
     Dyndeps const& dyndeps = ddi->second;
     if (!UpdateEdge(edge, &dyndeps, err)) {
       return false;

src/dyndep.h

@@ -27,8 +27,6 @@ struct State;
 /// Store dynamically-discovered dependency information for one edge.
 #if 1 
 struct Dyndeps {
-  Dyndeps() : used_(false){}
-  bool used_;
   std::vector<Node*> implicit_inputs_;
 };
 #else