Drop trailing path separators in getPermissions on Windows

This fixes the issue haskell#9 where Windows fails to recognize paths that
contain trailing path separators.

System/Directory.hs

@@ -197,7 +197,8 @@ The operation may fail with:
 getPermissions :: FilePath -> IO Permissions
 getPermissions name = do
 #ifdef mingw32_HOST_OS
-  withFilePath name $ \s -> do
+  -- issue #9: Windows doesn't like trailing path separators
+  withFilePath (dropTrailingPathSeparator name) $ \s -> do
   -- stat() does a better job of guessing the permissions on Windows
   -- than access() does.  e.g. for execute permission, it looks at the
   -- filename extension :-)

tests/getPermissions001.hs

@@ -1,13 +1,17 @@
 import System.Directory
 
 main = do
+#ifndef mingw32_HOST_OS
+  let exe = ".exe"
+#else
+  let exe = ""
+#endif
   p <- getPermissions "."
   print p
   p <- getPermissions "getPermissions001.hs"
   print p
-#ifndef mingw32_HOST_OS
-  p <- getPermissions "getPermissions001"
-#else
-  p <- getPermissions "getPermissions001.exe"
-#endif
+  p <- getPermissions ("getPermissions001" ++ exe)
   print p
+
+  -- issue #9: Windows doesn't like trailing path separators
+  _ <- getPermissions "../tests/"