Move description of win/setup_toolchain.py before import.

Moved description just before import, and it should make the file description more looks like so.

Review URL: https://codereview.chromium.org/932813002

Cr-Original-Commit-Position: refs/heads/master@{#316597}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 1a5679784256b268d2fd46ae7d501b02a265c36d

toolchain/win/setup_toolchain.py

@@ -1,13 +1,7 @@
 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
-
-import errno
-import os
-import re
-import subprocess
-import sys
-
+#
 # Copies the given "win tool" (which the toolchain uses to wrap compiler
 # invocations) and the environment blocks for the 32-bit and 64-bit builds on
 # Windows to the build directory.
@@ -16,6 +10,12 @@ import sys
 # win tool. The script assumes that the root build directory is the current dir
 # and the files will be written to the current directory.
 
+import errno
+import os
+import re
+import subprocess
+import sys
+
 
 def _ExtractImportantEnvironment(output_of_set):
   """Extracts environment variables required for the toolchain to run from