store location of loop boundary

Since lowering always inserts gotos and other instructions after loop
bodies, this allows debuggers to give a more useful location for these
instructions.

fixes JuliaDebug/JuliaInterpreter.jl#485

src/julia-parser.scm

@@ -1376,14 +1376,14 @@
             (if (eq? word 'quote)
                 (list 'quote blk)
                 blk))))
-       ((while)  (begin0 (list 'while (parse-cond s) (parse-block s))
+       ((while)  (begin0 (list 'while (parse-cond s) (append (parse-block s) (list (line-number-node s))))
                          (expect-end s word)))
        ((for)
         (let* ((ranges (parse-comma-separated-iters s))
                (body   (parse-block s)))
           (expect-end s word)
           `(for ,(if (length= ranges 1) (car ranges) (cons 'block ranges))
-                ,body)))
+                ,(append body (list (line-number-node s))))))
 
        ((let)
         (let ((binds (if (memv (peek-token s) '(#\newline #\;))