StoreArgsInStackSlot sometimes does unaligned store.

Relate to commit 18469ec4.
In MemoryFill, size is an 8-byte integer, but is stored into a
4-byte aligned memory;

Bug: v8:10949, chromium:1281995
Change-Id: I9f18a0168432cdd6d27eacc98b980fa5b6d57d79
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3447932Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Yu Liu <liuyu@loongson.cn>
Cr-Commit-Position: refs/heads/main@{#79019}