fix rbtrees built from ordered lists

fix jt
be more flexible about unbound parents


git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@2260 b08c6af1-5177-4d33-ba66-4b1c6b8b522a

C/tracer.c

@@ -164,6 +164,8 @@ low_level_trace(yap_low_level_port port, PredEntry *pred, CELL *args)
   LOCK(Yap_heap_regs->low_level_trace_lock);
   sc = Yap_heap_regs;
   vsc_count++;
+  if (vsc_count < 67689000LL)
+    return;
 #ifdef THREADS
   Yap_heap_regs->thread_handle[worker_id].thread_inst_count++;
 #endif