THRIFT-2401 Haskell tutorial compiles

Patch: John Chee & Roger Meier

includes minifix from:
THRIFT-2453 haskell tutorial: fix up division by 0 example
diff --git a/tutorial/Makefile.am b/tutorial/Makefile.am
index 6fc9209..ccc9c46 100755
--- a/tutorial/Makefile.am
+++ b/tutorial/Makefile.am
@@ -42,6 +42,10 @@
 SUBDIRS += rb
 endif
 
+if WITH_HASKELL
+SUBDIRS += hs
+endif
+
 if WITH_GO
 SUBDIRS += go
 endif