cmd: re-enable tests with external linking on openbsd/arm

Go on openbsd/arm has supported external linking for a while now, so
re-enable the external linking related tests that were previously
disabled.

Fixes #10619

Change-Id: I304eeabf3b462d53b7feda17ae390bbe2fa22069
Reviewed-on: https://go-review.googlesource.com/c/go/+/173597Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/go/note_test.go

@@ -32,8 +32,6 @@ func TestNoteReading(t *testing.T) {
 	switch {
 	case !build.Default.CgoEnabled:
 		t.Skipf("skipping - no cgo, so assuming external linking not available")
-	case runtime.GOOS == "openbsd" && runtime.GOARCH == "arm":
-		t.Skipf("skipping - external linking not supported, golang.org/issue/10619")
 	case runtime.GOOS == "plan9":
 		t.Skipf("skipping - external linking not supported")
 	}

src/cmd/objdump/objdump_test.go

@@ -194,10 +194,6 @@ func TestDisasmExtld(t *testing.T) {
 	case "s390x":
 		t.Skipf("skipping on %s, issue 15255", runtime.GOARCH)
 	}
-	// TODO(jsing): Reenable once openbsd/arm has external linking support.
-	if runtime.GOOS == "openbsd" && runtime.GOARCH == "arm" {
-		t.Skip("skipping on openbsd/arm, no support for external linking, issue 10619")
-	}
 	if !build.Default.CgoEnabled {
 		t.Skip("skipping because cgo is not enabled")
 	}