[Py2to3] A group of small compatiblity code changes

* Replace the uses of long with int.
 * Replace im_func with __func__ as it has been provided for Python 3 forward-compatibility.
 * Fix next/__next__ for Python 3 compatibility.
 * Remove the long number literal
 * Ensure freespace() returns int

msgfmt.py

@@ -86,7 +86,7 @@ def generate():
         voffsets += [l2, o2 + valuestart]
     offsets = koffsets + voffsets
     output = struct.pack("Iiiiiii",
-                         0x950412deL,       # Magic
+                         0x950412de,       # Magic
                          0,                 # Version
                          len(keys),         # # of entries
                          7 * 4,             # start of key index