Add boost-system dependencies (bis)

setup.py

@@ -52,6 +52,7 @@ setup(
           "xbob/io/video/version.cpp",
           ],
         packages = packages,
+        boost_modules = ['system'],
         include_dirs = include_dirs,
         version = version,
         define_macros = [('__STDC_CONSTANT_MACROS', None)],
@@ -68,7 +69,6 @@ setup(
           "xbob/io/video/main.cpp",
           ],
         packages = packages,
-        boost_modules = ['system'],
         include_dirs = include_dirs,
         version = version,
         define_macros = [('__STDC_CONSTANT_MACROS', None)],