ninja win: filter 64 bit idl processing, and confirm in test

Windows x64 build otherwise emits noise like:

"
64 bit Processing ..\..\third_party\iaccessible2\ia2_api_all.idl

ia2_api_all.idl
"

Suppress that, and confirm in existing test.

R=thakis@chromium.org

Review URL: https://codereview.chromium.org/298863003

git-svn-id: http://gyp.googlecode.com/svn/trunk@1922 78cadc50-ecff-11dd-a971-7dbc132099af