Imported Upstream version 4.3.2.467

Former-commit-id: 9c2cb47f45fa221e661ab616387c9cda183f283d

external/referencesource/System.ServiceModel/System/ServiceModel/Channels/UnsafeNativeMethods.cs

@@ -1099,6 +1099,12 @@ namespace System.ServiceModel.Channels
             [MarshalAs(UnmanagedType.U1), Out] out bool pfEnabled
             );
 
+
+#if !FEATURE_CORECLR
+        // On CoreCLR this is not the way to determine if a process is a tailored application (which means APPX).
+        // On CoreCLR AppX is determined by a flag past to the host which is exposed by AppDomain.IsAppXProcess in mscorlib.
+        // The reason for this if-def is to ensure nobody takes a dependency on this on CoreCLR.
+        
         // AppModel.h functions (Win8+)
         [DllImport(KERNEL32, CharSet = CharSet.None, EntryPoint = "GetCurrentPackageId")]
         [SecurityCritical]
@@ -1128,6 +1134,7 @@ namespace System.ServiceModel.Channels
         /// Indicates weather the running application is an immersive (or modern) Windows 8 (or later) application.
         /// </summary>
         internal static Lazy<bool> IsTailoredApplication = new Lazy<bool>(() => _IsTailoredApplication());
+#endif //!FEATURE_CORECLR
     }
 
     [SuppressUnmanagedCodeSecurity]