adds conditional export of useXDG in non-windows OS-es. fix in rmGhcupDirs code that used useXDG

lib/GHCup.hs

@@ -1370,7 +1370,7 @@ rmGhcupDirs = do
 
     rmBinDir binDir = do
 #if !defined(IS_WINDOWS)
-      isXDGStyle <- useXDG
+      isXDGStyle <- liftIO $ useXDG
       if not isXDGStyle
         then removeDirIfEmpty binDir
         else pure ()

lib/GHCup/Utils/Dirs.hs

@@ -27,6 +27,9 @@ module GHCup.Utils.Dirs
   , relativeSymlink
   , withGHCupTmpDir
   , getConfigFilePath
+#if !defined(IS_WINDOWS)
+  , useXDG
+#endif
   )
 where