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>

testing_support/trial_dir.py

@@ -2,6 +2,7 @@
 # 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 atexit
 import logging
@@ -93,5 +94,5 @@ class TestCase(auto_stub.TestCase, TrialDirMixIn):
 if '-l' in sys.argv:
   # See SHOULD_LEAK definition in TrialDir for its purpose.
   TrialDir.SHOULD_LEAK = True
-  print 'Leaking!'
+  print('Leaking!')
   sys.argv.remove('-l')