Fixed "RC4011: identifier truncated" warning when embedding manifests.
    
Including <winuser.h> directly caused the following warning on VS2010:
    
  string.h(54) : warning RC4011: identifier truncated to '_CRT_SECURE_CPP_OVERLOAD_STANDA'

R=scottmg@chromium.org

Review URL: https://chromiumcodereview.appspot.com/19284012

git-svn-id: http://gyp.googlecode.com/svn/trunk@1677 78cadc50-ecff-11dd-a971-7dbc132099af