util: Allow customization of the logger

The customization is necessary for Android and NS-3 builds

Change-Id: I8f799bfae63bd97c566eade812c575a7397ae223
diff --git a/src/util/logging.hpp b/src/util/logging.hpp
index 96e1bcb..45dbe07 100644
--- a/src/util/logging.hpp
+++ b/src/util/logging.hpp
@@ -24,6 +24,10 @@
 
 #include "../common.hpp"
 
+#ifdef HAVE_NDN_CXX_CUSTOM_LOGGER
+#include "ndn-cxx-custom-logging.hpp"
+#else
+
 #include <boost/log/sinks.hpp>
 #include <mutex>
 #include <unordered_map>
@@ -184,4 +188,6 @@
 } // namespace util
 } // namespace ndn
 
+#endif // HAVE_NDN_CXX_CUSTOM_LOGGER
+
 #endif // NDN_UTIL_LOGGING_HPP