core: architecture dependent part in thread_t

core/include/thread.h

@@ -209,10 +209,10 @@ struct _thread {
     const char *name;               /**< thread's name                  */
     int stack_size;                 /**< thread's stack size            */
 #endif
-#ifdef HAVE_THREAD_ARCH_EXT_T 
-    thread_arch_ext_t arch;         /**< architecture dependent exten- 
-                                         sions                          */ 
-#endif };
+#ifdef HAVE_THREAD_ARCH_T
+    thread_arch_t arch;             /**< architecture dependent part    */
+#endif
+};
 
 /**
  * @def THREAD_STACKSIZE_DEFAULT