cmd/link: move to cmd/newlink

In preparation for making the current linker cmd/link.
If cmd/newlink is ever completed, it can be moved back.

See golang-dev thread titled "go tool compile, etc" for background.

Change-Id: I4029580f470038240c5181a37ea4202ba971f9ef
Reviewed-on: https://go-review.googlesource.com/10286Reviewed-by: Rob Pike <r@golang.org>

misc/nacl/testzip.proto

@@ -35,7 +35,7 @@ go	src=..
 				gofmt_test.go
 				testdata
 					+
-			link
+			newlink
 				testdata
 					+
 		archive

src/cmd/dist/build.go

@@ -374,7 +374,7 @@ var oldtool = []string{
 // Unreleased directories (relative to $GOROOT) that should
 // not be in release branches.
 var unreleased = []string{
-	"src/cmd/link",
+	"src/cmd/newlink",
 	"src/cmd/objwriter",
 	"src/debug/goobj",
 	"src/old",

src/cmd/go/pkg.go

@@ -412,7 +412,7 @@ var goTools = map[string]targetDir{
 	"cmd/dist":                             toTool,
 	"cmd/doc":                              toTool,
 	"cmd/fix":                              toTool,
-	"cmd/link":                             toTool,
+	"cmd/newlink":                          toTool,
 	"cmd/nm":                               toTool,
 	"cmd/objdump":                          toTool,
 	"cmd/old5a":                            toTool,