Convert print statements to Python 3 style

Ran "2to3 -w -n -f print ./" and manually added imports.
Ran "^\s*print " and "\s+print " to find batch/shell scripts, comments and the like with embedded code, and updated them manually.
Also manually added imports to files, which used print as a function, but were missing the import.

The scripts still work with Python 2.
There are no intended behaviour changes.

Bug: 942522
Change-Id: Id777e4d4df4adcdfdab1b18bde89f235ef491b9f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1595684
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Dirk Pranke <dpranke@chromium.org>
Auto-Submit: Raul Tambre <raul@tambre.ee>
diff --git a/git_footers.py b/git_footers.py
index 6749181..ad091b5 100755
--- a/git_footers.py
+++ b/git_footers.py
@@ -3,6 +3,8 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+from __future__ import print_function
+
 import argparse
 import json
 import re
@@ -229,23 +231,23 @@
 
   if opts.key:
     for v in footers.get(normalize_name(opts.key), []):
-      print v
+      print(v)
   elif opts.position:
     pos = get_position(footers)
-    print '%s@{#%s}' % (pos[0], pos[1] or '?')
+    print('%s@{#%s}' % (pos[0], pos[1] or '?'))
   elif opts.position_ref:
-    print get_position(footers)[0]
+    print(get_position(footers)[0])
   elif opts.position_num:
     pos = get_position(footers)
     assert pos[1], 'No valid position for commit'
-    print pos[1]
+    print(pos[1])
   elif opts.json:
     with open(opts.json, 'w') as f:
       json.dump(footers, f)
   else:
     for k in footers.keys():
       for v in footers[k]:
-        print '%s: %s' % (k, v)
+        print('%s: %s' % (k, v))
   return 0