Add support for F32x4AddHoriz, I32x4AddHoriz, I16x8AddHoriz
operations for mips32 and mips64 architectures.

Bug: 
Change-Id: I5a40f23677418ffd81d4d5229203a439545575b8
Reviewed-on: https://chromium-review.googlesource.com/518016
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Mircea Trofin <mtrofin@chromium.org>
Reviewed-by: Bill Budge <bbudge@chromium.org>
Reviewed-by: Miran Karić <Miran.Karic@imgtec.com>
Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Cr-Commit-Position: refs/heads/master@{#46272}