Besides, implement i64x2 signed compares in liftoff.

Port: a38039a7
Port: b57a0d19

Bug: v8:11415
Change-Id: I18e9bdbf346daacbb53595e504f14a32aedcfc07
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2711725Reviewed-by: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Auto-Submit: Liu yu <liuyu@loongson.cn>
Cr-Commit-Position: refs/heads/master@{#72887}