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

Change-Id: Icc370968e3d38fef80ece35a2aed56450f54b653
diff --git a/wscript b/wscript
index 15cb62d..aef4320 100644
--- a/wscript
+++ b/wscript
@@ -1,6 +1,6 @@
 # -*- Mode: python; py-indent-offset: 4; indent-tabs-mode: nil; coding: utf-8; -*-
 """
-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,
@@ -144,7 +144,7 @@
     # or conf.define_cond().  Everything that was added directly to conf.env.DEFINES
     # will not appear in the config header, but will instead be passed directly to the
     # compiler on the command line.
-    conf.write_config_header('core/config.hpp')
+    conf.write_config_header('core/config.hpp', define_prefix='NFD_')
 
 def build(bld):
     versionhpp(bld)