This integrates the build files for the loader SDK, and tests the
compilation by calling InitInstance. There's no current way to
test the runtime behaviour since there's no way for the tests to
initialize the Vulkan back-end, that will come in the next CL.

BUG=angleproject:1319

Change-Id: Ia8bf96ca068eaf40744c9753b59ffaaa5ada8a73
Reviewed-on: https://chromium-review.googlesource.com/367519
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>