Cycles: Cleanup, don't use strict C prototypes

Those are more like a legacy of language, which is not
needed in C++.

intern/cycles/util/util_thread.h

@@ -46,14 +46,14 @@ typedef std::condition_variable thread_condition_variable;
 
 class thread {
 public:
-	thread(function<void(void)> run_cb, int group = -1);
+	thread(function<void()> run_cb, int group = -1);
 	~thread();
 
 	static void *run(void *arg);
 	bool join();
 
 protected:
-	function<void(void)> run_cb_;
+	function<void()> run_cb_;
 	std::thread thread_;
 	bool joined_;
 	int group_;