build: Fixing gcc compilation

Change-Id: I925de1d5a687398a918d1b41826cb44e2c1ea170
diff --git a/src/util/time.hpp b/src/util/time.hpp
index 16bc4db..90482d9 100644
--- a/src/util/time.hpp
+++ b/src/util/time.hpp
@@ -9,7 +9,7 @@
 #define NDN_TIME_HPP
 
 #include <stdexcept>
-#include <ndn-cpp/c/util/time.h>
+#include "../c/util/time.h"
 
 namespace ndn {