cmd/compile: use "missing method m" instead of "missing m method"

cmd/compile: use "missing method m" instead of "missing m method"

For #55326

Change-Id: I3d0ff7f820f7b2009d1b226abf701b2337fe8cbc
Reviewed-on: https://go-review.googlesource.com/c/go/+/432635
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: xie cui <523516579@qq.com>
Reviewed-by: Robert Griesemer <gri@google.com>