Imported Upstream version 5.20.0.180

Former-commit-id: ff953ca879339fe1e1211f7220f563e1342e66cb

mcs/class/corlib/System/BitConverter.cs

@@ -0,0 +1,23 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.CompilerServices;
+
+namespace System
+{
+	public static partial class BitConverter
+	{
+		[Intrinsic]
+		public static readonly bool IsLittleEndian;
+
+		static BitConverter ()
+		{
+			unsafe {
+				ushort i = 0x1234;
+				byte *b = (byte*)&i;
+				IsLittleEndian = (*b == 0x34);
+			}
+		}
+	}
+}