Improve detection of inability to check free disk space.

Don't check if configure indicated checks won't work. This should fix a
FTBFS on mipsel, where configure correctly detects the checks won't work,
while garbage is returned for disk space info at git-annex runtime. It also
means that, when built via cabal, disk space checks are not enabled,
unfortunatly.

Build/Configure.hs

@@ -10,8 +10,12 @@ import Control.Applicative
 import Build.TestConfig
 import Utility.SafeCommand
 
-tests :: [TestCase]
-tests =
+tests :: Bool -> [TestCase]
+tests True = cabaltests ++ common
+tests False = common
+
+common :: [TestCase]
+common =
 	[ TestCase "version" getVersion
 	, TestCase "git" $ requireCmd "git" "git --version >/dev/null"
 	, TestCase "git version" getGitVersion
@@ -28,6 +32,11 @@ tests =
 	, TestCase "ssh connection caching" getSshConnectionCaching
 	] ++ shaTestCases [1, 256, 512, 224, 384]
 
+cabaltests :: [TestCase]
+cabaltests =
+	[ TestCase "StatFS" testStatFSDummy
+	]
+
 shaTestCases :: [Int] -> [TestCase]
 shaTestCases l = map make l
 	where make n =
@@ -72,6 +81,10 @@ getSshConnectionCaching :: Test
 getSshConnectionCaching = Config "sshconnectioncaching" . BoolConfig <$>
 	boolSystem "sh" [Param "-c", Param "ssh -o ControlPersist=yes -V >/dev/null 2>/dev/null"]
 
+testStatFSDummy :: Test
+testStatFSDummy = 
+	return $ Config "statfs_sanity_checked" $ MaybeBoolConfig Nothing
+
 {- Set up cabal file with version. -}
 cabalSetup :: IO ()
 cabalSetup = do