pretty-printer: Properly parenthesise LastStmt

After ApplicatveDo strips the last `return` during renaming, the pretty
printer has to restore it. However, if the return was followed by `$`,
the dollar was stripped too and not restored.

For example, the last stamement in:

```
  foo = do
    x <- ...
    ...
    return $ f x
```

would be printed as:

```
    return f x
```

This commit preserved the dolar, so it becomes:

```
    return $ f x
```

1 files changed, 10 insertions, 0 deletions

diff --git a/testsuite/tests/ado/ado009.hs b/testsuite/tests/ado/ado009.hs
new file mode 100644
index 0000000000..876a4fba90
--- /dev/null
+++ b/testsuite/tests/ado/ado009.hs
@@ -0,0 +1,10 @@
+{-# LANGUAGE ApplicativeDo #-}
+{-# OPTIONS_GHC -ddump-rn -dsuppress-uniques #-}
+
+module Test where
+
+-- Make sure the $ stripped from the last stmt is printed
+q :: IO ()
+q = do
+  a <- return ()
+  return $ (\_ -> ()) a