Respect newlines before "where"

source/library/Language/Haskell/Brittany/Internal/ToBriDoc/Decl.hs

@@ -238,7 +238,10 @@ layoutGrhs (L _ (GRHS epAnn guards body)) = do
   guardDocs <- case guards of
     [] -> pure []
     _  -> docFlushCommsPost False posArrow $ callLayouter layout_stmt `mapM` guards
-  bodyDoc <- callLayouter layout_expr body
+  let bodyEndPos = case locA $ getLoc body of
+        GHC.RealSrcSpan s _ -> Just s
+        GHC.UnhelpfulSpan{} -> Nothing
+  bodyDoc <- docFlushCommsPost True bodyEndPos $ callLayouter layout_expr body
   return (Just epAnn, guardDocs, bodyDoc)
 
 layoutPatternBind