Imported Upstream version 4.2.0.179

Former-commit-id: 0a113cb3a6feb7873f632839b1307cc6033cd595

mcs/class/corlib/ReferenceSources/BCLDebug.cs

@@ -41,5 +41,15 @@ namespace System
 		internal static void Perf (bool expr, string msg)
 		{
 		}
+
+		[Conditional("_LOGGING")]
+		public static void Trace (string switchName, params object[]messages)
+		{
+		}
+
+		internal static bool CheckEnabled (string switchName)
+		{
+			return false;
+		}
 	}
 }