Change -X flags into LANGUAGE pragmas

compiler/cmm/CmmBuildInfoTables.hs

-{-# OPTIONS_GHC -XGADTs -XNoMonoLocalBinds #-}
+{-# LANGUAGE GADTs, NoMonoLocalBinds #-}
 {-# OPTIONS -fno-warn-tabs #-}
 -- The above warning supression flag is a temporary kludge.
 -- While working on this module you are encouraged to remove it and
@@ -7,8 +7,8 @@
 -- for details
 
 -- Norman likes local bindings
--- If this module lives on I'd like to get rid of the -XNoMonoLocalBinds
--- flag in due course
+-- If this module lives on I'd like to get rid of the NoMonoLocalBinds
+-- extension in due course
 
 -- Todo: remove -fno-warn-warnings-deprecations
 {-# OPTIONS_GHC -fno-warn-warnings-deprecations #-}

compiler/cmm/CmmPipeline.hs

-{-# OPTIONS_GHC -XNoMonoLocalBinds #-}
+{-# LANGUAGE NoMonoLocalBinds #-}
 -- Norman likes local bindings
--- If this module lives on I'd like to get rid of this flag in due course
+-- If this module lives on I'd like to get rid of this extension in due course
 
 module CmmPipeline (
   -- | Converts C-- with an implicit stack and native C-- calls into

compiler/cmm/CmmStackLayout.hs

-{-# OPTIONS_GHC -XGADTs -XNoMonoLocalBinds #-}
+{-# LANGUAGE GADTs, NoMonoLocalBinds #-}
 -- Norman likes local bindings
--- If this module lives on I'd like to get rid of the -XNoMonoLocalBinds
--- flag in due course
+-- If this module lives on I'd like to get rid of the NoMonoLocalBinds
+-- extension in due course
 
 {-# OPTIONS -fno-warn-tabs #-}
 -- The above warning supression flag is a temporary kludge.

compiler/typecheck/TcGenDeriv.lhs

@@ -11,7 +11,9 @@ This module is nominally ``subordinate'' to @TcDeriv@, which is the
 This is where we do all the grimy bindings' generation.
 
 \begin{code}
-{-# OPTIONS -fno-warn-tabs -XScopedTypeVariables #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+
+{-# OPTIONS -fno-warn-tabs #-}
 -- The above warning supression flag is a temporary kludge.
 -- While working on this module you are encouraged to remove it and
 -- detab the module (please do the detabbing in a separate patch). See

compiler/utils/UniqFM.lhs

@@ -20,7 +20,9 @@ and ``addToUFM\_C'' and ``Data.IntMap.insertWith'' differ in the order
 of arguments of combining function.
 
 \begin{code}
-{-# OPTIONS -fno-warn-tabs -XGeneralizedNewtypeDeriving #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+
+{-# OPTIONS -fno-warn-tabs #-}
 -- The above warning supression flag is a temporary kludge.
 -- While working on this module you are encouraged to remove it and
 -- detab the module (please do the detabbing in a separate patch). See