include: Add SIGDN enumeration.

include/shobjidl.idl

@@ -346,7 +346,17 @@ interface IShellFolder2 : IShellFolder
 ]
 interface IShellItem : IUnknown
 {
-    typedef DWORD SIGDN;
+    typedef [v1_enum] enum {
+        SIGDN_NORMALDISPLAY                = 0,
+        SIGDN_PARENTRELATIVEPARSING        = 0x80018001,
+        SIGDN_DESKTOPABSOLUTEPARSING       = 0x80028000,
+        SIGDN_PARENTRELATIVEEDITING        = 0x80031001,
+        SIGDN_DESKTOPABSOLUTEEDITING       = 0x8004c000,
+        SIGDN_FILESYSPATH                  = 0x80058000,
+        SIGDN_URL                          = 0x80068000,
+        SIGDN_PARENTRELATIVEFORADDRESSBAR  = 0x8007c001,
+        SIGDN_PARENTRELATIVE               = 0x80080001
+    } SIGDN; /* & 0xFFFF => SHGDN */
 
     typedef DWORD SICHINTF;