Use newtype deriving for Hoopl code

Hoopl.Collections/.Label has newtype containers which derive
Functor/Traversable.
Enabling GeneralizedNewtypeDeriving improves allocation count and
compile time when building these files for GHC.

```
Vanilla, O1
<<ghc: 378555664 bytes, 76 GCs, 8663140/18535016 avg/max bytes
residency (5 samples), 63M in use, 0.000 INIT (0.000 elapsed), 0.219
MUT (0.354 elapsed), 0.141 GC (0.138 elapsed) :ghc>>

GeneralizedNewtypeDeriving , O1
<<ghc: 301026536 bytes, 78 GCs, 8392886/17181088 avg/max bytes
residency (5 samples), 63M in use, 0.000 INIT (0.000 elapsed), 0.156
MUT (0.230 elapsed), 0.094 GC (0.106 elapsed) :ghc>>
```

Test Plan: ci

Reviewers: bgamari, simonmar, RyanGlScott

Reviewed By: RyanGlScott

Subscribers: mpickering, RyanGlScott, thomie, carter

Differential Revision: https://phabricator.haskell.org/D4583

compiler/cmm/Hoopl/Collections.hs

@@ -2,6 +2,8 @@
 {-# LANGUAGE DeriveTraversable #-}
 {-# LANGUAGE DeriveFoldable #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+
 module Hoopl.Collections
     ( IsSet(..)
     , setInsertList, setDeleteList, setUnions

compiler/cmm/Hoopl/Label.hs

@@ -2,6 +2,8 @@
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE DeriveTraversable #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+
 module Hoopl.Label
     ( Label
     , LabelMap