use fmap instead of importing Applicative

Importing Applicative into this module causes the instances in
Control.Monad.Instances to leak into the Haskell 98 module System,
which would break Haskell 98 programs that define these instances.

System/Process/Internals.hs

@@ -55,7 +55,6 @@ import Data.IORef
 #endif
 #endif
 
-import Control.Applicative
 import System.IO 	( Handle )
 import System.Exit	( ExitCode )
 import Control.Concurrent
@@ -396,7 +395,7 @@ mbFd fun _std (UseHandle hdl) = withHandle_ fun hdl $ return . haFD
 mbFd _   _std CreatePipe      = return (-1)
 
 mbPipe :: StdStream -> Ptr FD -> IOMode -> IO (Maybe Handle)
-mbPipe CreatePipe pfd  mode = Just <$> pfdToHandle pfd mode
+mbPipe CreatePipe pfd  mode = fmap Just (pfdToHandle pfd mode)
 mbPipe _std      _pfd _mode = return Nothing
 
 pfdToHandle :: Ptr FD -> IOMode -> IO Handle