Writing out the number of functions in the module is unnecessary. That
number is only used for validation when reading back the value, but only
validating that number is pretty arbitrary and does not protect against
bugs or attacks. Hence skip these two header fields.

R=thibaudm@chromium.org

Bug: v8:11164
Change-Id: I083075e2c8959f99690fd1478d0950a25eb7311f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2644946
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72326}