work on gpu clocks and gpu turbo example

examples/gpu_clocks.cu

@@ -1,5 +1,18 @@
+#include <iostream>
+
 #include "perfect/gpu_clocks.hpp"
+#include "perfect/init.hpp"
 
 int main(void) {
 
+    using namespace perfect;
+
+    init();
+
+    for (unsigned int gpu = 0; gpu < 1; ++gpu) {
+      PERFECT(perfect::set_max_gpu_clocks(gpu));
+      PERFECT(perfect::reset_gpu_clocks(gpu));
+    }
+
+    return 0;
 }