Reland "Reuse arch/mode discovery in deopt fuzzer"

This is a reland of a24c7c9a
Original change's description:
> Reuse arch/mode discovery in deopt fuzzer
> 
> Bug: v8:6917
> Change-Id: I1b7169c8702c8649812b17579d38d64de676ed60
> Reviewed-on: https://chromium-review.googlesource.com/723420
> Commit-Queue: Michał Majewski <majeski@google.com>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#48838}

Bug: v8:6917
Change-Id: I03b2c288257d44c2df9d0fa6cf4750d1c5719d59
Reviewed-on: https://chromium-review.googlesource.com/735719
Commit-Queue: Michał Majewski <majeski@google.com>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48916}