Cap the number of aapt2 daemons to 6

Author: dellis1972

src/Xamarin.Android.Build.Tasks/Tasks/Aapt2.cs

@@ -21,6 +21,7 @@ namespace Xamarin.Android.Tasks {
 
 	public abstract class Aapt2 : AndroidAsyncTask {
 
+		private static readonly int DefaultMaxAapt2Daemons = 6;
 		protected Dictionary<string, string> resource_name_case_map;
 		public int DaemonMaxInstanceCount { get; set; }
 
@@ -64,7 +65,9 @@ protected virtual int GetRequiredDaemonInstances ()
 		public override bool Execute ()
 		{
 			// Must register on the UI thread!
-			int maxInstances = Environment.ProcessorCount-1;
+			// We don't want to use up ALL the available cores especially when 
+			// running in the IDE. So lets cap it at DefaultMaxAapt2Daemons (6).
+			int maxInstances = Math.Min (Environment.ProcessorCount-1, DefaultMaxAapt2Daemons);
 			if (DaemonMaxInstanceCount == 0)
 				DaemonMaxInstanceCount = maxInstances;
 			else