Included Option pragma

- included OPTION_GHC pragma
- and removed unnecessary tab in module where clause

snippets/haskell.snippets

@@ -2,6 +2,8 @@ snippet lang
 	{-# LANGUAGE ${0:OverloadedStrings} #-}
 snippet haddock
 	{-# OPTIONS_HADDOCK ${0:hide} #-}
+snippet ghc
+	{-# OPTIONS_GHC ${0:-fno-warn-unused-imports} #-}
 snippet inline
 	{-# INLINE ${0:name} #-}
 snippet info