Imported Upstream version 5.0.0.42

Former-commit-id: fd56571888259555122d8a0f58c68838229cea2b

mcs/class/WindowsBase/ZipSharp/NativeVersion.cs

@@ -0,0 +1,20 @@
+using System;
+
+namespace zipsharp {
+	static class NativeVersion {
+
+		/// <summary>
+		/// ZipSharp code needs different code paths
+		/// depending on the size of the C long type on the underlying platform. On
+		/// gcc/clang the C long type follows the bitness of the targeted architecture,
+		/// it's 32-bit on 32-bit systems and 64-bit on 64-bit systems. With the VS
+		/// compiler however, the C long type is always 32-bit regardless of the
+		/// target architecture. zlib and minizip uses C long in a number of 
+		/// different function signatures and structs. 
+		/// 
+		/// This field is used to easily determine if the 32 bit version of 
+		/// functions and structs should be used when interacting with zlib.
+		/// </summary>
+		public static readonly bool Use32Bit = IntPtr.Size == 4 || Environment.OSVersion.Platform != PlatformID.Unix;
+	}
+}