Globally ignore '*_excluded' keys for MSVS Settings
Globally ignore '*_excluded' keys for MSVS Settings

This extends validation of MSVS settings to ignore any key found that is suffixed with '_excluded', but still verifies that the root key name is a valid setting.

Patch from Eric N. Vander Weele <ericvw@gmail.com>

R=scottmg@chromium.org

Review URL: https://codereview.chromium.org/175873002
witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp,witwall/gyp