THRIFT-4717: fix up make clean with autoconf
diff --git a/tutorial/hs/Makefile.am b/tutorial/hs/Makefile.am
index a3eccc2..9c6fd83 100755
--- a/tutorial/hs/Makefile.am
+++ b/tutorial/hs/Makefile.am
@@ -27,7 +27,12 @@
 # Make sure this doesn't fail if Haskell is not configured.
 clean-local:
 	$(CABAL) clean
-	$(RM) -r gen-*
+	$(RM) -r dist/
+	$(RM) -r gen-*/
+
+dist-hook:
+	$(RM) -r $(distdir)/dist/
+	$(RM) -r $(distdir)/gen-*/
 
 check-local:
 	$(CABAL) check