build: prepend "NFD_" to various macro names to avoid conflicts

Change-Id: Icc370968e3d38fef80ece35a2aed56450f54b653
diff --git a/daemon/face/websocketpp.hpp b/daemon/face/websocketpp.hpp
index 022682b..4815ed1 100644
--- a/daemon/face/websocketpp.hpp
+++ b/daemon/face/websocketpp.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018,  Regents of the University of California,
+ * Copyright (c) 2014-2021,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -26,9 +26,11 @@
 #ifndef NFD_DAEMON_FACE_WEBSOCKETPP_HPP
 #define NFD_DAEMON_FACE_WEBSOCKETPP_HPP
 
-#ifndef HAVE_WEBSOCKET
+#include "core/config.hpp"
+
+#ifndef NFD_HAVE_WEBSOCKET
 #error "Cannot include this file when WebSocket support is disabled"
-#endif // HAVE_WEBSOCKET
+#endif
 
 // suppress websocketpp warnings
 #pragma GCC system_header