pin hsc2hs as an extra-dep

kadoban · kadoban · commit baf9a6ba09cd · 2017-08-31T11:02:35.000-07:00
Hopefully this will get it built automatically on appveyor when
we need it.
diff --git a/stack.yaml b/stack.yaml
@@ -24,3 +24,4 @@ extra-deps:
 - path-io-1.3.3
 - extra-1.6
 - monad-logger-0.3.25
+- hsc2hs-0.68.2
