[accounts] Update for beta 2 (#4297)

src/accounts.cs

@@ -40,7 +40,7 @@ namespace Accounts {
 		NSString ErrorDomain { get; }
 #endif
 
-		[iOS (7,0)][Mac (10,14, onlyOn64: true)]
+		[iOS (7,0)][NoMac]
 		[Export ("userFullName")]
 		string UserFullName { get; }
 	}
@@ -84,6 +84,9 @@ namespace Accounts {
 		[Async]
 		void SaveAccount (ACAccount account, ACAccountStoreSaveCompletionHandler completionHandler);
 
+#if XAMCORE_4_0
+		[NoMac] // marked as unavailable in xcode10 beta 2
+#endif
 		[Export ("requestAccessToAccountsWithType:withCompletionHandler:")]
 		[Availability (Deprecated = Platform.iOS_6_0, Message = "Use 'RequestAccess (ACAccountType, AccountStoreOptions, ACRequestCompletionHandler)' instead.")]
 		[Async]