OsPath transition Windows build fixes

This gets it building on Windows again, with 1 test suite failure
(addurl).

Sponsored-by: Kevin Mueller

Utility/Shell.hs

@@ -21,10 +21,6 @@ import Utility.Exception
 import Utility.PartialPrelude
 #endif
 
-#ifdef mingw32_HOST_OS
-import System.FilePath
-#endif
-
 shellPath :: FilePath
 shellPath = "/bin/sh"
 
@@ -46,13 +42,13 @@ findShellCommand f = do
 		Just ('#':'!':rest) -> case words rest of
 			[] -> defcmd
 			(c:ps) -> do
-				let ps' = map Param ps ++ [File f]
+				let ps' = map Param ps ++ [File (fromOsPath f)]
 				-- If the command is not inSearchPath,
 				-- take the base of it, and run eg "sh"
 				-- which in some cases on windows will work
 				-- despite it not being inSearchPath.
 				ok <- inSearchPath c
-				return (if ok then c else takeFileName c, ps')
+				return (if ok then c else fromOsPath (takeFileName (toOsPath c)), ps')
 		_ -> defcmd
 #endif
   where