Make NODE-DOTIMES hold a counter variable

wip-duuqnd/user-side-compiler/high-level.lisp

@@ -78,6 +78,8 @@
 (defclass node-dotimes (node)
   ((%stop-ref :accessor stop-ref :initarg :stop-ref
               :documentation "A reference giving a value of how many times to run the loop.")
+   (%counter-ref :accessor counter-ref :initarg :counter-ref
+                 :documentation "A reference to a variable being set to the loop index.")
    (%loopee-node :accessor loopee-node :initarg :loopee-node)))
 
 (defmethod generate-code ((node node-dotimes))