Reason for reland: Fixed Fuchsia build.
Original change's description:
> [builtins] Remap builtins on Linux
>
> This is a CL similar to
> https://chromium-review.googlesource.com/c/v8/v8/+/3553006, but on Linux
> rather than macOS. The goal is to allow builtins to use short builtin
> calls without paying a memory cost, by remapping rather than copying
> them.
>
> However, while macOS has a system call making this easier, on Linux we
> don't have one on most kernels. There is the recently-introduced
> mremap(MREMAP_DONTUNMMAP), which is available in 5.7, but only works on
> anonymous mappings until 5.13, which is too recent for most Android
> devices.
>
> Instead, we open() the file containing the builtins, and mmap() it at
> the desired location.
>
> Change-Id: I4524f349948b8f48c4536cf392a1cd179662a6cc
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3570426
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Reviewed-by: Jakob Linke <jgruber@chromium.org>
> Commit-Queue: Benoit Lize <lizeb@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#80022}
Change-Id: I0cc8cf510bd2cb8621130bea8406d79aa209948c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3596164
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Benoit Lize <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80049}
8d186bb453