Fixed SF bug #663074. The codec system was using global static
variables to store internal data. As a result, any atempts to use the
unicode system with multiple active interpreters, or successive
interpreter executions, would fail.

Now that information is stored into members of the PyInterpreterState
structure.
diff --git a/Include/pystate.h b/Include/pystate.h
index 3e5b5b4..f4c9d6e 100644
--- a/Include/pystate.h
+++ b/Include/pystate.h
@@ -22,6 +22,10 @@
     PyObject *sysdict;
     PyObject *builtins;
 
+    PyObject *codec_search_path;
+    PyObject *codec_search_cache;
+    PyObject *codec_error_registry;
+
 #ifdef HAVE_DLOPEN
     int dlopenflags;
 #endif