build: Adjust order of link flags

The previous order of flags (unintentionally) had `-lboost_log` flag
specified before `-lndn-cxx`.  Incidentally, the order adjustment avoids
a symbol collision between the two libraries that prevented nfd-status
and nfdc from working on Ubuntu 14.04. A proper fix will follow (see #2859).

Change-Id: I68a5d37b013c1bf91b25e707a04ab1f66298a7f4
Refs: #3650
diff --git a/wscript b/wscript
index f174342..206bb2d 100644
--- a/wscript
+++ b/wscript
@@ -181,7 +181,7 @@
         features='cxx pch',
         source=bld.path.ant_glob(['core/**/*.cpp'],
                                  excl=['core/logger*.cpp']),
-        use='version BOOST NDN_CXX LIBRT',
+        use='version NDN_CXX BOOST LIBRT',
         includes='. core',
         export_includes='. core',
         headers='common.hpp',