Test that chmod() actually exists before calling it (it doesn't on MacOS9).

Lib/fileinput.py

@@ -309,6 +309,7 @@ class FileInput:
                                      perm)
                         self._output = os.fdopen(fd, "w")
                         try:
+                            if hasattr(os, 'chmod'):
                                 os.chmod(self._filename, perm)
                         except OSError:
                             pass