Clang: Remove unused functions

Change-Id: Id5bf1852b308ef84d8cfd575a60f084326729ac2
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/clangcodemodel/clangbackendcommunicator.h

@@ -113,13 +113,6 @@ public:
 
     bool isNotWaitingForCompletion() const;
 
-public: // for tests
-    BackendSender *setBackendSender(BackendSender *sender);
-    void killBackendProcess();
-
-signals: // for tests
-    void backendReinitialized();
-
 private:
     void initializeBackend();
     void initializeBackendWithCurrentData();