[dev.typeparams] runtime/internal/sys: replace GOOS with goos.GOOS

Refactoring done by rf tool:

    rf 'ex . {
	import "internal/goos"
	import "runtime/internal/sys"
	sys.GOOS -> goos.GOOS
    }'

Change-Id: I4b4aadff8640731ce4cb9bdad9954c267eb484c8
Reviewed-on: https://go-review.googlesource.com/c/go/+/328339
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
diff --git a/src/runtime/extern.go b/src/runtime/extern.go
index 1c70e8a..eca4062 100644
--- a/src/runtime/extern.go
+++ b/src/runtime/extern.go
@@ -188,7 +188,7 @@
 
 import (
 	"internal/goarch"
-	"runtime/internal/sys"
+	"internal/goos"
 )
 
 // Caller reports file and line number information about function invocations on
@@ -263,7 +263,7 @@
 // GOOS is the running program's operating system target:
 // one of darwin, freebsd, linux, and so on.
 // To view possible combinations of GOOS and GOARCH, run "go tool dist list".
-const GOOS string = sys.GOOS
+const GOOS string = goos.GOOS
 
 // GOARCH is the running program's architecture target:
 // one of 386, amd64, arm, s390x, and so on.
diff --git a/src/runtime/internal/sys/consts.go b/src/runtime/internal/sys/consts.go
index 07fbaf4..4d45f9d 100644
--- a/src/runtime/internal/sys/consts.go
+++ b/src/runtime/internal/sys/consts.go
@@ -80,8 +80,6 @@
 	GoarchWasm        = goarch.GoarchWasm
 )
 
-const GOOS = goos.GOOS
-
 const (
 	GoosAix       = goos.GoosAix
 	GoosAndroid   = goos.GoosAndroid