add regression test for symlink calculation

Note: Test reordered because running git-annex sync early broke the
environment for some other tests.

Utility/Path.hs

@@ -47,6 +47,7 @@ absNormPath dir path = Just $ combine dir path
 
 {- On Windows, this converts the paths to unix-style, in order to run
  - MissingH's absNormPath on them. Resulting path will use / separators. -}
+absNormPathUnix :: FilePath -> FilePath -> Maybe FilePath
 #ifndef mingw32_HOST_OS
 absNormPathUnix dir path = MissingH.absNormPath dir path
 #else