[gyp] Disable warnings generated by third party ICU code.
[gyp] Disable warnings generated by third party ICU code.

R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/962523002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#26871}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh