remove warning

Author: Johannes Waldmann

containers/src/Data/Set/Internal.hs

@@ -1865,7 +1865,7 @@ data StrictTriple = ST !Int !Int !Int
 -- | return bitmask for upper half,
 -- index of middle bit, bitmask for lower half
 splitBits :: Int -> StrictTriple
-splitBits m | m > 0 =
+splitBits m =
   let go 0 !x = x; go k !x = go (k-1) (clearLowest x)
       !up_med = go (div (popCount m) 2) m
       !lo = xor m up_med