Add the tiger source code bundle from the book site

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

tiger/testcases/test5.tig

@@ -0,0 +1,14 @@
+/* define valid recursive types */
+let
+/* define a list */
+type intlist = {hd: int, tl: intlist} 
+
+/* define a tree */
+type tree ={key: int, children: treelist}
+type treelist = {hd: tree, tl: treelist}
+
+var lis:intlist := intlist { hd=0, tl= nil } 
+
+in
+	lis
+end