[subprocess2] Replace VOID with DEVNULL

subprocess.DEVNULL was introduced in Python3 to serve same purpose
as subprocess2.VOID, so rename VOID to DEVNULL in subprocess2.

Change-Id: I6dade3306ffc3bc2441ac6083f362b099c2427e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2587758
Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
diff --git a/roll_dep.py b/roll_dep.py
index ef19a36..371e15b 100755
--- a/roll_dep.py
+++ b/roll_dep.py
@@ -63,10 +63,10 @@
 
 def return_code(*args, **kwargs):
   """subprocess2.call() passing shell=True on Windows for git and
-  subprocess2.VOID for stdout and stderr."""
+  subprocess2.DEVNULL for stdout and stderr."""
   kwargs.setdefault('shell', NEED_SHELL)
-  kwargs.setdefault('stdout', subprocess2.VOID)
-  kwargs.setdefault('stderr', subprocess2.VOID)
+  kwargs.setdefault('stdout', subprocess2.DEVNULL)
+  kwargs.setdefault('stderr', subprocess2.DEVNULL)
   return subprocess2.call(*args, **kwargs)