Add Conditional Target capabilities to the build scripts

Make Attribute properties immutable

PR Feedback, bugfixes

PR Feedback

scripts/Microsoft.DotNet.Cli.Build.Framework/CurrentArchitecture.cs

@@ -0,0 +1,50 @@
+using System;
+using Microsoft.Extensions.PlatformAbstractions;
+
+namespace Microsoft.DotNet.Cli.Build.Framework
+{
+    public static class CurrentArchitecture
+    {
+        public static BuildArchitecture Current
+        {
+            get
+            {
+                return DetermineCurrentArchitecture();
+            }
+        }
+
+        public static bool Isx86
+        {
+            get
+            {
+                var archName = PlatformServices.Default.Runtime.RuntimeArchitecture;
+                return string.Equals(archName, "x86", StringComparison.OrdinalIgnoreCase);
+            }
+        }
+
+        public static bool Isx64
+        {
+            get
+            {
+                var archName = PlatformServices.Default.Runtime.RuntimeArchitecture;
+                return string.Equals(archName, "x64", StringComparison.OrdinalIgnoreCase);
+            }
+        }
+
+        private static BuildArchitecture DetermineCurrentArchitecture()
+        {
+            if (Isx86)
+            {
+                return BuildArchitecture.x86;
+            }
+            else if (Isx64)
+            {
+                return BuildArchitecture.x64;
+            }
+            else
+            {
+                return default(BuildArchitecture);
+            }
+        }
+    }
+}