Fix build on case-insensitive filesystems (#873)

GhcModExe/Boot.hs

@@ -0,0 +1,29 @@
+module GhcModExe.Boot where
+
+import Control.Applicative
+import Prelude
+
+import GhcModExe.Browse
+import GhcModExe.Flag
+import GhcModExe.Lang
+import GhcModExe.Modules
+import Language.Haskell.GhcMod.Monad
+import Language.Haskell.GhcMod.Types (defaultBrowseOpts)
+
+-- | Printing necessary information for front-end booting.
+boot :: IOish m => GhcModT m String
+boot = concat <$> sequence ms
+  where
+    ms = [modules False, languages, flags, concat <$> mapM (browse defaultBrowseOpts) preBrowsedModules]
+
+preBrowsedModules :: [String]
+preBrowsedModules = [
+    "Prelude"
+  , "Control.Applicative"
+  , "Control.Exception"
+  , "Control.Monad"
+  , "Data.Char"
+  , "Data.List"
+  , "Data.Maybe"
+  , "System.IO"
+  ]