add tak function benchmark file

etc/tak.scm

@@ -0,0 +1,21 @@
+(define start #f)
+
+(define end #f)
+
+(define (time f)
+  (set! start (current-jiffy))
+  (f)
+  (set! end (current-jiffy))
+  (/ (- end start) (jiffies-per-second)))
+
+(define (tak x y z)
+  (if (> x y)
+      (tak (tak (- x 1) y z) 
+	   (tak (- y 1) z x)
+	   (tak (- z 1) x y))
+      y))
+
+(define (f)
+  (tak 12 6 0))
+
+(write (time f))