Bug 1883570 - Build OSPreferences for iOS. r=platform-i18n-reviewers,dminor

We can use the same as the one for mac, as long as we use the headers
their SDKs have in common.

Differential Revision: https://phabricator.services.mozilla.com/D203562

intl/locale/mac/OSPreferences_mac.cpp

@@ -6,7 +6,8 @@
 
 #include "OSPreferences.h"
 #include "mozilla/intl/LocaleService.h"
-#include <Carbon/Carbon.h>
+#include <CoreFoundation/CoreFoundation.h>
+#include <CoreText/CoreText.h>
 
 using namespace mozilla::intl;
 

intl/locale/moz.build

@@ -14,7 +14,7 @@ toolkit = CONFIG["MOZ_WIDGET_TOOLKIT"]
 
 if toolkit == "windows":
     DIRS += ["windows"]
-elif toolkit == "cocoa":
+elif toolkit in ("cocoa", "uikit"):
     DIRS += ["mac"]
 elif toolkit == "gtk":
     DIRS += ["gtk"]