Fix cctests to maintain an aligned stack pointer, and delete a couple
that don't make sense if only an aligned stack pointer is allowed.

Bug: v8:6644
Change-Id: Ib825df0f93515ec408169018eb97ab587f1f14b6
Reviewed-on: https://chromium-review.googlesource.com/808386Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Martyn Capewell <martyn.capewell@arm.com>
Cr-Commit-Position: refs/heads/master@{#49866}