Cover case within autoLowLikelihood where no matches are present

Why?
====

In cases where no matchers are present, a language config should not
auto-classify every match as low-likelihood; instead, it should return
False so subsequent checks can operate on the match itself.

This is related to 9bf9499e67f52bcde2420bfe3945f73cfdaa06d7; both are
handling cases where less configuration data than ideal is present and
the program still needs to operate correctly.

src/Unused/ResponseFilter.hs

@@ -47,7 +47,8 @@ autoLowLikelihood l r =
     classOrModule = classOrModuleFunction . smClassOrModule
 
     matchesToBool :: [Matcher] -> Bool
-    matchesToBool = all (`matcherToBool` r)
+    matchesToBool [] = False
+    matchesToBool a = all (`matcherToBool` r) a
 
 classOrModuleFunction :: Bool -> TermResults -> Bool
 classOrModuleFunction True = isClassOrModule

test/Unused/ResponseFilterSpec.hs

@@ -128,6 +128,14 @@ spec = parallel $ do
 
             haskellAutoLowLikelihood result `shouldReturn` True
 
+    describe "autoLowLikelihood" $
+        it "doesn't qualify as low when no matchers are present in a language config" $ do
+            let match = TermMatch "AwesomeThing" "app/foo/awesome_thing.rb" 1
+            let result = resultsFromMatches [match]
+            let languageConfig = LanguageConfiguration "Bad" [] [LowLikelihoodMatch "Match with empty matchers" [] False] []
+
+            autoLowLikelihood languageConfig result `shouldBe` False
+
 configByName :: String -> IO LanguageConfiguration
 configByName s = do
     (Right config) <- loadConfig