fixed python binding build on Mac OS and BSD

bindings/python/src/session.cpp

@@ -2,11 +2,9 @@
 // subject to the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
+#include <boost/python.hpp>
 #include <list>
 #include <string>
-#include "Python.h"
-#include <cctype>
-#include <boost/python.hpp>
 #include <libtorrent/session.hpp>
 #include <libtorrent/settings.hpp> // for bencode_map_entry
 #include <libtorrent/torrent.hpp>