cmd/dist: omit dragonfly/386 GOOS/GOARCH pair

dragonfly/386 isn't a valid GOOS/GOARCH pair.

Change-Id: I44374a932b20f0d49b2e509484143970eb5464c2
Reviewed-on: https://go-review.googlesource.com/79656
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/dist/test.go

@@ -784,7 +784,7 @@ func (t *tester) extLink() bool {
 	switch pair {
 	case "android-arm",
 		"darwin-arm", "darwin-arm64",
-		"dragonfly-386", "dragonfly-amd64",
+		"dragonfly-amd64",
 		"freebsd-386", "freebsd-amd64", "freebsd-arm",
 		"linux-386", "linux-amd64", "linux-arm", "linux-arm64", "linux-ppc64le", "linux-mips64", "linux-mips64le", "linux-mips", "linux-mipsle", "linux-s390x",
 		"netbsd-386", "netbsd-amd64",
@@ -930,7 +930,7 @@ func (t *tester) cgoTest(dt *distTest) error {
 		t.addCmd(dt, "misc/cgo/test", "go", "test", "-ldflags", "-linkmode=external")
 		t.addCmd(dt, "misc/cgo/test", "go", "test", "-ldflags", "-linkmode=external -s")
 	case "android-arm",
-		"dragonfly-386", "dragonfly-amd64",
+		"dragonfly-amd64",
 		"freebsd-386", "freebsd-amd64", "freebsd-arm",
 		"linux-386", "linux-amd64", "linux-arm", "linux-ppc64le", "linux-s390x",
 		"netbsd-386", "netbsd-amd64":