Ported godefs to Windows.

R=rsc
https://golang.org/cl/164049
diff --git a/lib/codereview/codereview.py b/lib/codereview/codereview.py
index fa535d6..f5bb8fc 100644
--- a/lib/codereview/codereview.py
+++ b/lib/codereview/codereview.py
@@ -171,6 +171,8 @@
 		f = open(path+'!', "w")
 		f.write(self.DiskText())
 		f.close()
+		if sys.platform == "win32" and os.path.isfile(path):
+			os.remove(path)
 		os.rename(path+'!', path)
 		if self.web and not self.original_author:
 			EditDesc(self.name, desc=self.desc,