Remove the buffer API from PyUnicode as specified by PEP 3137.  Also,
fix the error message of the 't' format unit, in getargs.c, so that it
asks for bytes, instead of string.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 75ce991..2fe2b63 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -2135,7 +2135,8 @@
     FILEFINDBUF3   ep;
     APIRET rc;
 
-    if (!PyArg_ParseTuple(args, "t#:listdir", &name, &len))
+    if (!PyArg_ParseTuple(args, "et#:listdir", 
+                          Py_FileSystemDefaultEncoding, &name, &len))
         return NULL;
     if (len >= MAX_PATH) {
 		PyErr_SetString(PyExc_ValueError, "path too long");