Bug 30605: Honor privacy.spoof_english in Android

This checks `privacy.spoof_english` whenever `setLocales` is
called from Fenix side and sets `intl.accept_languages`
accordingly.

mobile/android/components/geckoview/GeckoViewStartup.jsm

@@ -18,6 +18,7 @@ XPCOMUtils.defineLazyModuleGetters(this, {
   Preferences: "resource://gre/modules/Preferences.jsm",
   SafeBrowsing: "resource://gre/modules/SafeBrowsing.jsm",
   Services: "resource://gre/modules/Services.jsm",
+  RFPHelper: "resource://gre/modules/RFPHelper.jsm",
 });
 
 const { debug, warn } = GeckoViewUtils.initLogging("Startup");
@@ -256,6 +257,10 @@ class GeckoViewStartup {
         if (aData.requestedLocales) {
           Services.locale.requestedLocales = aData.requestedLocales;
         }
+        RFPHelper._handleSpoofEnglishChanged();
+        if (Services.prefs.getIntPref("privacy.spoof_english", 0) === 2) {
+          break;
+        }
         const pls = Cc["@mozilla.org/pref-localizedstring;1"].createInstance(
           Ci.nsIPrefLocalizedString
         );