[xharness] Exclude bcl tests by default.

tests/xharness/Jenkins.cs

@@ -13,6 +13,7 @@ namespace xharness
 	{
 		public Harness Harness;
 		public bool IncludeClassic;
+		public bool IncludeBcl;
 
 		public string LogDirectory {
 			get {
@@ -95,6 +96,9 @@ namespace xharness
 				if (!project.IsExecutableProject)
 					continue;
 
+				if (!IncludeBcl && project.Path.Contains ("bcl-test"))
+					continue;
+
 				var build = new XBuildTask ()
 				{
 					Jenkins = this,