[dev.boringcrypto] cmd/link: allow internal linking for crypto/internal/boring

Change-Id: I5b122ad23f75296dab8cec89a4e50dcca7fa9b3f
Reviewed-on: https://go-review.googlesource.com/57944
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/go_boring_test.go

@@ -0,0 +1,20 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main_test
+
+import "testing"
+
+func TestBoringInternalLink(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.tempFile("main.go", `package main
+		import "crypto/sha1"
+		func main() {
+			sha1.New()
+		}`)
+	tg.run("build", "-ldflags=-w -extld=false", tg.path("main.go"))
+	tg.run("build", "-ldflags=-extld=false", tg.path("main.go"))
+}

src/cmd/link/internal/ld/lib.go

@@ -856,6 +856,7 @@ var hostobj []Hostobj
 // These packages can use internal linking mode.
 // Others trigger external mode.
 var internalpkg = []string{
+	"crypto/internal/boring",
 	"crypto/x509",
 	"net",
 	"os/user",