Honor restricted_to for build
Honor restricted_to for build

Summary:
restricted_to is used to restrict certain targets to only build/run under
specific configurations (e.g. Darwin vs Linux). We were already using it for
testing; this change also uses it for building.

Reviewers: shahms

Reviewed By: shahms

Subscribers: #core_team

Differential Revision: https://phabricator-dot-kythe-repo.appspot.com/D2014

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