app/internal/window: [iOS] move logic out of GioAppDelegate

We'd like to remove GioAppDelegate when Gio is embedded with
gogio's -buildmode=archive. Minimize the code in GioAppDelegate.

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

app/internal/window/os_ios.go

@@ -309,3 +309,8 @@ func NewWindow(win Callbacks, opts *Options) error {
 
 func Main() {
 }
+
+//export gio_runMain
+func gio_runMain() {
+	runMain()
+}