Fix Aot to use TaskScheduler.Current

Author: dellis1972

src/Xamarin.Android.Build.Tasks/Tasks/Aot.cs

@@ -267,7 +267,7 @@ bool RunParallelAotCompiler (List<string> nativeLibs)
 
 				ThreadingTasks.ParallelOptions options = new ThreadingTasks.ParallelOptions {
 					CancellationToken = cts.Token,
-					TaskScheduler = ThreadingTasks.TaskScheduler.Default,
+					TaskScheduler = ThreadingTasks.TaskScheduler.Current,
 				};
 
 				ThreadingTasks.Parallel.ForEach (GetAotConfigs (), options,