This fills the padding between builtins in the embedded blob with a
sequence of int3 instructions (ia32,x64).

Drive-by: Unify code zapping. We can add better support for other
architectures later.

Bug: v8:6666
Change-Id: Ibcb120ec18a8062d7527e0c6fe5ca86869c0dad8
Reviewed-on: https://chromium-review.googlesource.com/1167050
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54976}