Added missing #include

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403690

examples/linear_manifold_regularizer_ex.cpp

@@ -90,6 +90,7 @@
 #include "dlib/statistics.h"
 #include <iostream>
 #include <vector>
+#include <ctime>
 
 
 using namespace std;