This is a reland of 21b3181a

Original change's description:
> PPC/s390: [wasm-simd][liftoff] Implement i8x16.popcnt
>
> Port 00babf07
>
> Original Commit Message:
>
>     Extract i8x16.popcnt implementation into a macro-assembler function, and
>     reuse it in Liftoff.
>
> R=zhin@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
> BUG=
> LOG=N
>
> Change-Id: Id0f14597a97f90424aa450b2527ea71da1b2e8ce
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2679273
> Reviewed-by: Junliang Yan <junyan@redhat.com>
> Commit-Queue: Junliang Yan <junyan@redhat.com>
> Cr-Commit-Position: refs/heads/master@{#72601}

Change-Id: I396a3f2ee85550df3a8fa92cd6357e7dc6f096a0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2685364Reviewed-by: Milad Fa <mfarazma@redhat.com>
Commit-Queue: Junliang Yan <junyan@redhat.com>
Cr-Commit-Position: refs/heads/master@{#72627}