This reverts commit b07c92a12d39e1ac51fe0dab8e4cb98f91f0d213.

Reason for revert: the litmus test of running this code on linux x86 bots
worked. However, performance-wise we're not so sure. Back this change out
to restrict it to Intel x64 for now.

Original change's description:
> Add x86 bots to the read64le party
>
> thestig@ reminds me we do have linux x86 bots on the waterfall. Add them
> to the read64le party. Minor: run git cl format over BUILD.gn, and add a
> line space here and there for readability.
>
> Bug: 760853
> Change-Id: Ia47296a26bff77f9be699e31053d8b94aac583f4
> Reviewed-on: https://chromium-review.googlesource.com/910328


> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Commit-Queue: Noel Gordon <noel@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#535612}

TBR=noel@chromium.org,mtklein@chromium.org,nigeltao@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 760853
Change-Id: If3d24a2cdc6614ff82c781019623108a52dbd16a
Reviewed-on: https://chromium-review.googlesource.com/913029


Commit-Queue: Noel Gordon <noel@chromium.org>
Reviewed-by: Noel Gordon <noel@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#536020}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b7fef3927da4a703c523e7e8916fd8d4c031a402