Enable back parallel sync on cygwin.

Cygwin used to have a bug where the number of lock was very limited, causing it
to crash when --jobs was used with a value different than 1. This bug seems to
have been fixed a few months ago as I can't reproduce the anymore after
extensive usage.

R=cmp@chromium.org
BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10689194

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@146798 0039d316-1c4b-4281-b951-d872f2087c98

gclient.py

@@ -1515,8 +1515,8 @@ def GenUsage(parser, command):
 def Parser():
   """Returns the default parser."""
   parser = optparse.OptionParser(version='%prog ' + __version__)
-  # cygwin and some arm boards have issues with parallel sync.
-  if sys.platform == 'cygwin' or platform.machine().startswith('arm'):
+  # some arm boards have issues with parallel sync.
+  if platform.machine().startswith('arm'):
     jobs = 1
   else:
     jobs = 8