cmd/gomobile: enable the test for gomobile-build on iOS

As golang/go#32963 has been fixed, gomobile-build test on iOS now
works.

Updates golang/go#32963

Change-Id: I96add914d1f97de6506f26e4ae0c07e8c884cb6a
Reviewed-on: https://go-review.googlesource.com/c/mobile/+/214957
Run-TryBot: Hajime Hoshi <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Trust: Hajime Hoshi <[email protected]>
Reviewed-by: Hyang-Ah Hana Kim <[email protected]>

Author: hajimehoshi

cmd/gomobile/build_test.go

@@ -208,10 +208,6 @@ func TestBuildWithGoModules(t *testing.T) {
 
 	for _, target := range []string{"android", "ios"} {
 		t.Run(target, func(t *testing.T) {
-			if target == "ios" {
-				t.Skip("gomobile-build doesn't work for iOS. see https://golang.org/issue/32963")
-			}
-
 			switch target {
 			case "android":
 				androidHome := os.Getenv("ANDROID_HOME")