Implement EmbedManifest handling for ninja windows.

BUG=gyp:321
R=alexeypa@chromium.org, scottmg@chromium.org

Review URL: https://codereview.chromium.org/17587022

git-svn-id: http://gyp.googlecode.com/svn/trunk@1655 78cadc50-ecff-11dd-a971-7dbc132099af