Windows: Support long filenames in more (possibly all) of the code

Works around this bug in unix-compat:
https://github.com/jacobstanley/unix-compat/issues/56
getFileStatus and other FilePath using functions in unix-compat do not do
UNC conversion on Windows.

Made Utility.RawFilePath use convertToWindowsNativeNamespace to do the
necessary conversion on windows to support long filenames.

Audited all imports of System.PosixCompat.Files to make sure that no
functions that operate on FilePath were imported from it. Instead, use
the equvilants from Utility.RawFilePath. In particular the
re-export of that module in Common had to be removed, which led to lots
of other changes throughout the code.

The changes to Build.Configure, Build.DesktopFile, and Build.TestConfig
make Utility.Directory not be needed to build setup. And so let it use
Utility.RawFilePath, which depends on unix, which cannot be in
setup-depends.

Sponsored-by: Dartmouth College's Datalad project

P2P/Address.hs

@@ -14,8 +14,10 @@ import Git.Types
 import Creds
 import Utility.AuthToken
 import Utility.Tor
+import qualified Utility.RawFilePath as R
 
 import qualified Data.Text as T
+import System.PosixCompat.Files (fileOwner, fileGroup)
 
 -- | A P2P address, without an AuthToken.
 --
@@ -80,8 +82,9 @@ storeP2PAddress addr = do
 		-- This may be run by root, so make the creds file
 		-- and directory have the same owner and group as
 		-- the git repository directory has.
-		st <- liftIO . getFileStatus =<< Annex.fromRepo repoLocation
-		let fixowner f = setOwnerAndGroup f (fileOwner st) (fileGroup st)
+		st <- liftIO . R.getFileStatus . toRawFilePath
+			=<< Annex.fromRepo repoLocation
+		let fixowner f = R.setOwnerAndGroup (toRawFilePath f) (fileOwner st) (fileGroup st)
 		liftIO $ do
 			fixowner tmpf
 			fixowner (takeDirectory tmpf)