Force a compiler release when we terminate the Renderer. Forcing the release ensures we always manually deallocate resources, and allows us to compile for different shader model versions after releasing the renderer. BUG=angle:619 Change-Id: I0c9d68a454c7779a024f4fcc4f4987c2abe12e60 Reviewed-on: https://chromium-review.googlesource.com/196820 Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Nicolas Capens <nicolascapens@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>