This has to be checked in first so it can be rolled in the next CL for this bug.

Description:
Add support for component=shared_library for base_unittests.

R=jshin@chromium.org
BUG=336439

Review URL: https://codereview.chromium.org/143903004

git-svn-id: https://src.chromium.org/chrome/trunk/deps/third_party/icu46@246118 4ff67af0-8c30-449e-8e8b-ad334ec8d88c