Use input_api.sys instead of import sys

Follow up on https://crrev.com/c/2929386

R=dpranke@google.com

Change-Id: Id977cfae561ecfb231372348387b084e098e6747
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2947981
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Dirk Pranke <dpranke@google.com>
Auto-Submit: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>

presubmit_canned_checks.py

@@ -944,7 +944,6 @@ def GetPylint(input_api,
   input_api.logging.debug('  with extra PYTHONPATH: %r', extra_paths_list)
 
   def GetPylintCmd(flist, extra, parallel):
-    import sys
     # Windows needs help running python files so we explicitly specify
     # the interpreter to use. It also has limitations on the size of
     # the command-line, so we pass arguments via a pipe.
@@ -976,7 +975,7 @@ def GetPylint(input_api,
       description += ' on %d cores' % input_api.cpu_count
 
     kwargs['stdin'] = '\n'.join(args + flist)
-    if sys.version_info.major != 2:
+    if input_api.sys.version_info.major != 2:
       kwargs['stdin'] = kwargs['stdin'].encode('utf-8')
 
     return input_api.Command(