fix infinite loop in inc_throwAway()

trainbenchmark-tool-jastadd-specialized-incremental/src/main/jastadd/intrinsics/nt-ref-list.jadd

@@ -182,4 +182,15 @@ aspect NTList {
   public boolean RefList.isEmpty() {
     return numChildren() == 0;
   }
+
+
+  refine ASTNode public void RefList.inc_throwAway() {
+    if (inc_throwAway_visited) {
+      return;
+    }
+    inc_throwAway_visited = true;
+    inc_state = inc_GARBAGE;
+    // super.inc_throwAway();
+    inc_throwAway_visited = false;
+  }
 }