cmd/internal/obj: set morestack arg spilling and regabi prologue on loong64

cmd/internal/obj: set morestack arg spilling and regabi prologue on loong64

Update #40724

Co-authored-by: Xiaolin Zhao <zhaoxiaolin@loongson.cn>
Change-Id: Ie92da57e29bae0e5cccb2a49a7cbeaf02cbf3a8d
Reviewed-on: https://go-review.googlesource.com/c/go/+/521787
Reviewed-by: Meidan Li <limeidan@loongson.cn>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: David Chase <drchase@google.com>