Issue #20978: pyflakes: fix undefined names

Lib/ftplib.py

@@ -320,7 +320,6 @@ class FTP:
                 raise err
             else:
                 raise OSError("getaddrinfo returns an empty list")
-            raise OSError(msg)
         sock.listen(1)
         port = sock.getsockname()[1] # Get proper port
         host = self.sock.getsockname()[0] # Get proper host

Lib/multiprocessing/connection.py

@@ -29,7 +29,7 @@ from .reduction import ForkingPickler
 
 try:
     import _winapi
-    from _winapi import WAIT_OBJECT_0, WAIT_TIMEOUT, INFINITE
+    from _winapi import WAIT_OBJECT_0, WAIT_ABANDONED_0, WAIT_TIMEOUT, INFINITE
 except ImportError:
     if sys.platform == 'win32':
         raise

Lib/tempfile.py

@@ -72,7 +72,7 @@ else:
     # file doesn't exist.
     def _stat(fn):
         fd = _os.open(fn, _os.O_RDONLY)
-        os.close(fd)
+        _os.close(fd)
 
 def _exists(fn):
     try: