[commit: ghc] master: Fix Windows build following D2588 (e39589e)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/e39589e2e4f788565c4a7f02cb85802214a95757/ghc

>---------------------------------------------------------------

commit e39589e2e4f788565c4a7f02cb85802214a95757
Author: Ryan Scott <ryan.gl.scott at gmail.com>
Date:   Fri Oct 14 22:28:29 2016 -0400

    Fix Windows build following D2588
    
    Commit 8c6a3d68c0301bb985aa2a462936bbcf7584ae9c inadvertently broke the build
    on Windows. This restores Windows compatibility.


>---------------------------------------------------------------

e39589e2e4f788565c4a7f02cb85802214a95757
 libraries/base/Data/Semigroup.hs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/libraries/base/Data/Semigroup.hs b/libraries/base/Data/Semigroup.hs
index 2cb1bb7..1c3d9da 100644
--- a/libraries/base/Data/Semigroup.hs
+++ b/libraries/base/Data/Semigroup.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                        #-}
 {-# LANGUAGE DefaultSignatures          #-}
 {-# LANGUAGE DeriveDataTypeable         #-}
 {-# LANGUAGE DeriveGeneric              #-}
@@ -83,7 +84,9 @@ import           Data.Monoid         (All (..), Any (..), Dual (..), Endo (..),
 import           Data.Monoid         (Alt (..))
 import qualified Data.Monoid         as Monoid
 import           Data.Void
-import           GHC.Event           (Event, Lifetime (..))
+#ifndef mingw32_HOST_OS
+import           GHC.Event           (Event, Lifetime)
+#endif
 import           GHC.Generics
 
 infixr 6 <>
@@ -711,6 +714,7 @@ instance Semigroup (Proxy s) where
 instance Semigroup a => Semigroup (IO a) where
     (<>) = liftA2 (<>)
 
+#ifndef mingw32_HOST_OS
 -- | @since 4.10.0.0
 instance Semigroup Event where
     (<>) = mappend
@@ -720,3 +724,4 @@ instance Semigroup Event where
 instance Semigroup Lifetime where
     (<>) = mappend
     stimes = stimesMonoid
+#endif