Re-organize directory structure (#4971)

See discussion in #2491

Co-authored-by: Ivan Levkivskyi <ilevkivskyi@dropbox.com>

stdlib/@python2/CGIHTTPServer.pyi

@@ -0,0 +1,6 @@
+import SimpleHTTPServer
+from typing import List
+
+class CGIHTTPRequestHandler(SimpleHTTPServer.SimpleHTTPRequestHandler):
+    cgi_directories: List[str]
+    def do_POST(self) -> None: ...