cmd/gio: drop 32-bit support for iOS

64-bit support was added in iOS 8 on iPhone 5S and newer,
32-bit support was dropped from iOS 12.

Gio is new and we have an opportunity to see if we can live without it.
We can always add 32-bit support back; it's harder to break users
later.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

cmd/gio/gio.go

@@ -83,10 +83,10 @@ func run(pkg string, appArgs []string) error {
 	}
 	var archs []string
 	switch *target {
-	case "tvos":
+	case "ios", "tvos":
 		// Only 64-bit support.
 		archs = []string{"arm64", "amd64"}
-	default:
+	case "android":
 		archs = []string{"arm", "arm64", "386", "amd64"}
 	}
 	if *archNames != "" {