compiler: further shrink test for #22.

Once this one passes, should also try pass_ext2-mount.cogent

cogent/tests/pass_ticket-e22-4.cogent

@@ -0,0 +1,35 @@
+type Result a b = <Success a | Error b>
+
+type Option a
+type WordArray a
+
+type FsState = {
+    superblock_num   : U32,
+    flags            : U32,
+    prealloc_offsets : Option (WordArray U32)
+}
+
+malloc_FsState: () -> Result (FsState take (..)) ()
+
+wordarray_create : all (a :< DS). () -> Result (WordArray a) ()
+
+free_FsState : FsState take (..) -> ()
+
+fs_mount: () -> Result FsState U32
+fs_mount _ =
+    malloc_FsState ()
+    | Success state_t -> 
+        let state_t = state_t { superblock_num = 1 }
+         in wordarray_create ()
+            | Success prealloc_offsets =>
+                let state = state_t {
+                      flags = 2,
+                      prealloc_offsets = Some prealloc_offsets
+                    }
+                in Success state
+            | Error _ ->
+                let _ = free_FsState state_t
+                in Error 1
+    | Error _ -> Error 2
+
+