Before this CL, cctest with component build will depend on the static v8
snapshot target and omit to dump the build configuration.

Now we simply write the configuration when building any v8
executable. In pure library builds, we don't need the configuration, as
it's used by the test framework to auto-detect testing options.

Bug: v8:5918
Change-Id: Ie85ba82a2803542f0a0c88d6044167138fdd7d4f
Reviewed-on: https://chromium-review.googlesource.com/554690Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46305}