core: move event-emitter to core

Change-Id: I76f6fc7d8c4731bbbb95ea257e339e15b96dbea1
diff --git a/tests/util/event-emitter.cpp b/tests/core/event-emitter.cpp
similarity index 98%
rename from tests/util/event-emitter.cpp
rename to tests/core/event-emitter.cpp
index 5f8d947..c44b6d2 100644
--- a/tests/util/event-emitter.cpp
+++ b/tests/core/event-emitter.cpp
@@ -4,9 +4,9 @@
  * See COPYING for copyright and distribution information.
  */
 
-#include <boost/test/unit_test.hpp>
+#include "core/event-emitter.hpp"
 
-#include "util/event-emitter.hpp"
+#include <boost/test/unit_test.hpp>
 
 namespace nfd {