Drop seemingly ineffective SPECIALISE pragmas

GHC HEAD warns about these:

```
Data/Sequence.hs:407:1: warning:
    SPECIALISE pragma for non-overloaded function ‘aptyMiddle’

Data/Sequence.hs:416:1: warning:
    SPECIALISE pragma for non-overloaded function ‘aptyMiddle’

Data/Sequence.hs:1001:1: warning:
    SPECIALISE pragma for non-overloaded function ‘cycleNMiddle’

Data/Sequence.hs:1007:1: warning:
    SPECIALISE pragma for non-overloaded function ‘cycleNMiddle’
```

Author: hvr

Data/Sequence.hs

@@ -404,25 +404,6 @@ aptyMiddle firstf
             (Two (fmap lastf pr) (fmap lastf q))
    where converted = node3 pr q sf
 
-{-# SPECIALIZE
- aptyMiddle
-  :: (Node c -> d)
-     -> (Node c -> d)
-     -> ((a -> b) -> Node c -> d)
-     -> FingerTree (Elem (a -> b))
-     -> Rigid (Node c)
-     -> FingerTree (Node d)
- #-}
-{-# SPECIALIZE
- aptyMiddle
-  :: (Elem c -> d)
-     -> (Elem c -> d)
-     -> ((a -> b) -> Elem c -> d)
-     -> FingerTree (Elem (a -> b))
-     -> Rigid (Elem c)
-     -> FingerTree (Node d)
- #-}
-
 digit12ToDigit :: Digit12 a -> Digit a
 digit12ToDigit (One12 a) = One a
 digit12ToDigit (Two12 a b) = Two a b
@@ -998,19 +979,6 @@ cycleNMiddle n
             (Two pr q)
    where converted = node3 pr q sf
 
-{-# SPECIALIZE
- cycleNMiddle
-  :: Int
-     -> Rigid (Node c)
-     -> FingerTree (Node (Node c))
- #-}
-{-# SPECIALIZE
- cycleNMiddle
-  :: Int
-     -> Rigid (Elem c)
-     -> FingerTree (Node (Elem c))
- #-}
-
 
 -- | /O(1)/. Add an element to the left end of a sequence.
 -- Mnemonic: a triangle with the single element at the pointy end.