Support rtems_ada_self iff __RTEMS_ADA__ is given.

cpukit/score/include/rtems/score/thread.h

@@ -331,8 +331,10 @@ struct Thread_Control_struct {
   boolean                               do_post_task_switch_extension;
   /** This field is true if the thread is preemptible. */
   boolean                               is_preemptible;
+#if __RTEMS_ADA__
   /** This field is the GNAT self context pointer. */
   void                                 *rtems_ada_self;
+#endif
   /** This field is the length of the time quantum that this thread is
    *  allowed to consume.  The algorithm used to manage limits on CPU usage
    *  is specified by budget_algorithm.

cpukit/score/src/threaddispatch.c

@@ -93,8 +93,10 @@ void _Thread_Dispatch( void )
     _Thread_Dispatch_disable_level = 1;
     _Context_Switch_necessary = FALSE;
     _Thread_Executing = heir;
+#if __RTEMS_ADA__
     executing->rtems_ada_self = rtems_ada_self;
     rtems_ada_self = heir->rtems_ada_self;
+#endif
     if ( heir->budget_algorithm == THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE )
       heir->cpu_time_budget = _Thread_Ticks_per_timeslice;
     _ISR_Enable( level );

cpukit/score/src/threadinitialize.c

@@ -63,11 +63,13 @@ boolean _Thread_Initialize(
   void                *extensions_area;
   boolean              extension_status;
 
+#if __RTEMS_ADA__
   /*
    *  Initialize the Ada self pointer
    */
 
   the_thread->rtems_ada_self = NULL;
+#endif
 
   /*
    *  Allocate and Initialize the stack for this thread.