Fixing hash escaping for msbuild.
Fixing hash escaping for msbuild.

Similar to:
http://code.google.com/p/gyp/source/detail?r=1388

BUG=None
TEST=None
R=thakis@chromium.org
Review URL: https://chromiumcodereview.appspot.com/10411071
old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google,old8xp/gyp_from_google