Explicitly print diff stats to sys.stdout, if possible.

This makes it possible to effectively re-route the stdout by
re-assigning sys.stdout.

BUG=

Review URL: https://codereview.chromium.org/303223005

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@273595 0039d316-1c4b-4281-b951-d872f2087c98

git_cl.py

@@ -259,10 +259,14 @@ def print_stats(similarity, find_copies, args):
   else:
     similarity_options = ['-M%s' % similarity]
 
+  try:
+    stdout = sys.stdout.fileno()
+  except AttributeError:
+    stdout = None
   return subprocess2.call(
       ['git',
        'diff', '--no-ext-diff', '--stat'] + similarity_options + args,
-      env=env)
+      stdout=stdout, env=env)
 
 
 class Settings(object):