add stress, os_perf_state_minimum, min-os-perf, max-os-perf

tools/min_os_perf.cpp

@@ -0,0 +1,9 @@
+#include "perfect/os_perf.hpp"
+
+int main(void) {
+  PERFECT(perfect::init());
+
+  for (auto cpu : perfect::cpus()) {
+    PERFECT(perfect::os_perf_state_minimum(cpu));
+  }
+}