This Mac/Fuchsia build was broken as the generated assembly file must
follow Linux-style calling conventions.

Change-Id: I05d946e77690e97f05d57a3d5ba04cd2e63fbb9d
Reviewed-on: https://chromium-review.googlesource.com/c/1377230
Commit-Queue: Fabrice de Gans-Riberi <fdegans@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Sergiy Belozorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58507}