cmd/dist: disable plugin test on linux-arm with GOARM=5

Plugin support is patchy at the moment, so disable the test for
now until the test can be fixed. This way, we can get builders
for ARMv5 running for the rest of the code.

Updates #19674

Change-Id: I08aa211c08a85688656afe2ad2e680a2a6e5dfac
Reviewed-on: https://go-review.googlesource.com/39716Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/dist/test.go

@@ -59,6 +59,7 @@ type tester struct {
 	goroot     string
 	goarch     string
 	gohostarch string
+	goarm      string
 	goos       string
 	gohostos   string
 	cgoEnabled bool
@@ -102,6 +103,7 @@ func (t *tester) run() {
 	t.gohostos = mustEnv("GOHOSTOS")
 	t.goarch = mustEnv("GOARCH")
 	t.gohostarch = mustEnv("GOHOSTARCH")
+	t.goarm = os.Getenv("GOARM")
 	slurp, err := exec.Command("go", "env", "CGO_ENABLED").Output()
 	if err != nil {
 		log.Fatalf("Error running go env CGO_ENABLED: %v", err)
@@ -782,6 +784,12 @@ func (t *tester) supportedBuildmode(mode string) bool {
 			return false
 		}
 
+		if pair == "linux-arm" && t.goarm == "5" {
+			// Skip the plugin tests for now on ARMv5 because it causes a
+			// SIGILL. See https://golang.org/issue/19674
+			return false
+		}
+
 		// linux-arm64 is missing because it causes the external linker
 		// to crash, see https://golang.org/issue/17138
 		switch pair {