commit b9c431aad6cc5383c9571007469eee8e64ec85a6
Author: Manoj Gupta <manojgupta@chromium.org>
Date:   Sat Nov 4 13:44:04 2017 -0700

    Fix powertop build with libc++.
    
    <ctime> header is not automatically included with libc++.
    Add it explicitly to make powertop build with libc++.
    
    This fixes the following errors:
    devices/gpu_rapl_device.cpp:35:14: error: use of undeclared identifier
    'time'; did you mean 'tie'?
    last_time = time(NULL);
                    ^~~~
    devices/gpu_rapl_device.cpp:45:14: error:use of undeclared identifier
    'time'; did you mean 'tie'?
    last_time = time(NULL);
                    ^~~~
    
    parameters/learn.cpp:161:10: error: use of undeclared identifier
    'time'; did you mean 'tie'?
    start =	time(NULL);
                ^~~~

diff --git a/src/lib.h b/src/lib.h
index b64bb0f..6d85eb6 100644
--- a/src/lib.h
+++ b/src/lib.h
@@ -54,7 +54,7 @@ extern const char *kernel_function(uint64_t address);
 
 
 
-
+#include <ctime>
 #include <string>
 using namespace std;