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

Change-Id: Icc370968e3d38fef80ece35a2aed56450f54b653
diff --git a/tests/test-common.hpp b/tests/test-common.hpp
index 9d4edbd..e25c6c9 100644
--- a/tests/test-common.hpp
+++ b/tests/test-common.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2020,  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,
@@ -31,7 +31,7 @@
 
 #include <ndn-cxx/prefix-announcement.hpp>
 
-#ifdef HAVE_PRIVILEGE_DROP_AND_ELEVATE
+#ifdef NFD_HAVE_PRIVILEGE_DROP_AND_ELEVATE
 #include <unistd.h>
 #define SKIP_IF_NOT_SUPERUSER() \
   do { \
@@ -42,7 +42,7 @@
   } while (false)
 #else
 #define SKIP_IF_NOT_SUPERUSER()
-#endif // HAVE_PRIVILEGE_DROP_AND_ELEVATE
+#endif // NFD_HAVE_PRIVILEGE_DROP_AND_ELEVATE
 
 namespace nfd {
 namespace tests {