fix warnings

by specifying which symbols we want to import.

the warnings were:
  src/System/Console/Hawk/Config.hs:200:17: Warning:
      This binding for `extensions' shadows the existing binding
        imported from `Language.Haskell.Exts' at src/System/Console/Hawk/Config.hs:14:1-28
        (and originally defined in `haskell-src-exts-1.13.5:Language.Haskell.Exts.ParseMonad')

  src/System/Console/Hawk/Config.hs:207:68: Warning:
      This binding for `name' shadows the existing binding
        imported from `Language.Haskell.Exts' at src/System/Console/Hawk/Config.hs:14:1-28
        (and originally defined in `Language.Haskell.Exts.Build')