enable deps mode on windows too

already enabled on non-windows. keeps use_deps=0 available as opt-out.

R=thakis@chromium.org
BUG=chromium:245034

Review URL: https://codereview.chromium.org/16925005

git-svn-id: http://gyp.googlecode.com/svn/trunk@1647 78cadc50-ecff-11dd-a971-7dbc132099af