bpo-30693: zip+tarfile: sort directory listing (#2263)

tarfile and zipfile now sort directory listing to generate tar and zip archives
in a more reproducible way.

See also https://reproducible-builds.org/docs/stable-inputs/ on that topic.
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 0b8d31f..a24ee42 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -1943,7 +1943,7 @@
         elif tarinfo.isdir():
             self.addfile(tarinfo)
             if recursive:
-                for f in os.listdir(name):
+                for f in sorted(os.listdir(name)):
                     self.add(os.path.join(name, f), os.path.join(arcname, f),
                             recursive, filter=filter)