Changing the rules on when to use the CLI's BuildRid.

Use the CLI's BuildRid when the current machine is not supported by the shared framework.

src/Microsoft.DotNet.Cli.Utils/FrameworkDependencyFile.cs

@@ -0,0 +1,45 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.IO;
+using System.Linq;
+using Microsoft.DotNet.InternalAbstractions;
+using Microsoft.Extensions.DependencyModel;
+
+namespace Microsoft.DotNet.Cli.Utils
+{
+    /// <summary>
+    /// Represents the .deps.json file in the shared framework
+    /// that the CLI is running against.
+    /// </summary>
+    internal class FrameworkDependencyFile
+    {
+        private readonly string _depsFilePath;
+
+        public FrameworkDependencyFile()
+        {
+            _depsFilePath = Muxer.GetDataFromAppDomain("FX_DEPS_FILE");
+        }
+
+        public bool IsCurrentRuntimeSupported()
+        {
+            return IsRuntimeSupported(RuntimeEnvironment.GetRuntimeIdentifier());
+        }
+
+        public bool IsRuntimeSupported(string runtimeIdentifier)
+        {
+            DependencyContext fxDependencyContext = CreateDependencyContext();
+
+            return fxDependencyContext.RuntimeGraph.Any(g => g.Runtime == runtimeIdentifier);
+        }
+
+        private DependencyContext CreateDependencyContext()
+        {
+            using (Stream depsFileStream = File.OpenRead(_depsFilePath))
+            using (DependencyContextJsonReader reader = new DependencyContextJsonReader())
+            {
+                return reader.Read(depsFileStream);
+            }
+        }
+    }
+}