rework cycle estimation

incl/iss/plugin/cycle_estimate.h

@@ -37,7 +37,6 @@
 
 #include "iss/instrumentation_if.h"
 #include "iss/vm_plugin.h"
-#include <json/json.h>
 #include <string>
 #include <unordered_map>
 
@@ -64,7 +63,7 @@ public:
 
     cycle_estimate(const cycle_estimate &&) = delete;
 
-    cycle_estimate(std::string config_file_name);
+    cycle_estimate(std::string const& config_file_name);
 
     virtual ~cycle_estimate();
 
@@ -88,7 +87,7 @@ private:
         }
     };
     std::unordered_map<std::pair<uint64_t, uint64_t>, uint64_t, pair_hash> blocks;
-    Json::Value root;
+    std::string config_file_name;
 };
 }
 }