build fix, relative path

Change-Id: I976a3dec39669a308596acbfc2366c402ee0fb05
diff --git a/src/algo/encrypt-params.cpp b/src/algo/encrypt-params.cpp
index 1e7a3a0..dd2afcf 100644
--- a/src/algo/encrypt-params.cpp
+++ b/src/algo/encrypt-params.cpp
@@ -17,7 +17,7 @@
  * gep, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "random-number-generator.hpp"
+#include "../random-number-generator.hpp"
 #include "encrypt-params.hpp"
 
 namespace ndn {