CL generated mechanically with github.com/mdempsky/unconvert.

Also updated cmd/compile/internal/ssa/gen/*.rules manually.

Change-Id: If721ef73cf0771ae83ce7e2d11623fc8d9155768
Reviewed-on: https://go-review.googlesource.com/97075Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>