This snapshot adds a marker section to the output assembly of
mksnapshot. Omitting this section can imply an executable stack, which
can result in linker warnings.

R=jgruber@chromium.org

Change-Id: I6f5dacb24de3a852faf6ce0caf18c32b499ba5a9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1687669
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62504}