more work on reserved/private pointer use

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@32182 72102866-910b-0410-8b05-ffd578937521

Headers/Foundation/NSThread.h

@@ -72,11 +72,14 @@ extern "C" {
   id			_gcontext;
   void                  *_runLoopInfo;  // Per-thread runloop related info.
 #endif
-#if     !GS_NONFRAGILE
+#if     GS_NONFRAGILE
+#else
   /* Pointer to private additional data used to avoid breaking ABI
    * when we don't have the non-fragile ABI available.
+   * Use this mechanism rather than changing the instance variable
+   * layout (see Source/GSInternal.h for details).
    */
-  void          *_reserved;
+  @private void *_internal GS_UNUSED_IVAR;
 #endif
 }