Don't build MshHostMshSnapin

src/Microsoft.PowerShell.ConsoleHost/singleshell/installer/MshHostMshSnapin.cs

@@ -1,3 +1,4 @@
+#if !OPEN
 /********************************************************************++
 Copyright (c) Microsoft Corporation.  All rights reserved.
 --********************************************************************/
@@ -92,3 +93,4 @@ namespace Microsoft.PowerShell
         }
     }
 }
+#endif