build: Fixing Linux compilation

Change-Id: Id7f521e2bd6d398b35192cf5c19471c4ebe32d0d
diff --git a/wscript b/wscript
index 96ffc85..ea64e92 100644
--- a/wscript
+++ b/wscript
@@ -109,7 +109,7 @@
         name = "ndn-cpp-dev",
         source = bld.path.ant_glob('src/**/*.cpp',
                                    excl = ['src/**/*-osx.cpp', 'src/**/*-sqlite3.cpp']),
-        use = 'BOOST OPENSSL LOG4CXX CRYPTOPP SQLITE3',
+        use = 'BOOST OPENSSL LOG4CXX CRYPTOPP SQLITE3 RT',
         includes = "src",
         export_includes = "src",
         )