misc/cgo/test,cmd/dist: enable (more) Cgo tests on iOS

For #15919

Change-Id: I9fc38d9c8a9cc9406b551315e1599750fe212d0d
Reviewed-on: https://go-review.googlesource.com/23635Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

misc/cgo/test/cthread.go

@@ -8,6 +8,7 @@ package cgotest
 import "C"
 
 import (
+	"runtime"
 	"sync"
 	"testing"
 )
@@ -30,6 +31,9 @@ func Add(x int) {
 }
 
 func testCthread(t *testing.T) {
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skip("the iOS exec wrapper is unable to properly handle the panic from Add")
+	}
 	sum.i = 0
 	C.doAdd(10, 6)
 

misc/cgo/test/issue7978.go

@@ -103,7 +103,7 @@ func test7978(t *testing.T) {
 	if C.HAS_SYNC_FETCH_AND_ADD == 0 {
 		t.Skip("clang required for __sync_fetch_and_add support on darwin/arm")
 	}
-	if runtime.GOOS == "android" {
+	if runtime.GOOS == "android" || runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
 		t.Skip("GOTRACEBACK is not passed on to the exec wrapper")
 	}
 	if os.Getenv("GOTRACEBACK") != "2" {

src/cmd/dist/test.go

@@ -465,11 +465,7 @@ func (t *tester) registerTests() {
 			})
 		}
 	}
-	if t.cgoEnabled && !t.iOS() {
-		// TODO(crawshaw): reenable on iOS
-		// golang.org/issue/15919
-		//
-		// These tests are not designed to run off the host.
+	if t.cgoEnabled {
 		t.tests = append(t.tests, distTest{
 			name:    "cgo_test",
 			heading: "../misc/cgo/test",
@@ -729,12 +725,6 @@ func (t *tester) runHostTest(dirBanner, pkg string) error {
 func (t *tester) cgoTest(dt *distTest) error {
 	env := mergeEnvLists([]string{"GOTRACEBACK=2"}, os.Environ())
 
-	if t.iOS() {
-		cmd := t.dirCmd("misc/cgo/test", "go", "test", t.tags())
-		cmd.Env = env
-		return cmd.Run()
-	}
-
 	cmd := t.addCmd(dt, "misc/cgo/test", "go", "test", t.tags(), "-ldflags", "-linkmode=auto", t.runFlag(""))
 	cmd.Env = env