all: remove the nacl port (part 1)

You were a useful port and you've served your purpose.
Thanks for all the play.

A subsequent CL will remove amd64p32 (including assembly files and
toolchain bits) and remaining bits. The amd64p32 removal will be
separated into its own CL in case we want to support the Linux x32 ABI
in the future and want our old amd64p32 support as a starting point.

Updates #30439

Change-Id: Ia3a0c7d49804adc87bf52a4dea7e3d3007f2b1cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/199499
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

internal/testenv/testenv.go

@@ -43,7 +43,7 @@ func HasGoBuild() bool {
 		return false
 	}
 	switch runtime.GOOS {
-	case "android", "nacl", "js":
+	case "android", "js":
 		return false
 	case "darwin":
 		if strings.HasPrefix(runtime.GOARCH, "arm") {
@@ -122,7 +122,7 @@ func GoTool() (string, error) {
 // using os.StartProcess or (more commonly) exec.Command.
 func HasExec() bool {
 	switch runtime.GOOS {
-	case "nacl", "js":
+	case "js":
 		return false
 	case "darwin":
 		if strings.HasPrefix(runtime.GOARCH, "arm") {
@@ -135,8 +135,6 @@ func HasExec() bool {
 // HasSrc reports whether the entire source tree is available under GOROOT.
 func HasSrc() bool {
 	switch runtime.GOOS {
-	case "nacl":
-		return false
 	case "darwin":
 		if strings.HasPrefix(runtime.GOARCH, "arm") {
 			return false
@@ -175,14 +173,14 @@ func MustHaveExecPath(t testing.TB, path string) {
 // HasExternalNetwork reports whether the current system can use
 // external (non-localhost) networks.
 func HasExternalNetwork() bool {
-	return !testing.Short() && runtime.GOOS != "nacl" && runtime.GOOS != "js"
+	return !testing.Short() && runtime.GOOS != "js"
 }
 
 // MustHaveExternalNetwork checks that the current system can use
 // external (non-localhost) networks.
 // If not, MustHaveExternalNetwork calls t.Skip with an explanation.
 func MustHaveExternalNetwork(t testing.TB) {
-	if runtime.GOOS == "nacl" || runtime.GOOS == "js" {
+	if runtime.GOOS == "js" {
 		t.Skipf("skipping test: no external network on %s", runtime.GOOS)
 	}
 	if testing.Short() {

internal/testenv/testenv_notwin.go

@@ -12,7 +12,7 @@ import (
 
 func hasSymlink() (ok bool, reason string) {
 	switch runtime.GOOS {
-	case "android", "nacl", "plan9":
+	case "android", "plan9":
 		return false, ""
 	}