fix warnings (#443)

Author: xuwei-k

io/src/main/scala/sbt/internal/nio/Globs.scala

@@ -67,9 +67,7 @@ private[sbt] object Globs {
             case _                                           => None
           }
         }
-      case AllPassFilter => Some(AnyPath)
-      case NothingFilter => Some(NoPath)
-      case _             => None
+      case _ => None
     }
   private[sbt] def nameFilterToRelativeGlob(nameFilter: NameFilter): Option[Matcher] =
     nameFilter match {

io/src/main/scala/sbt/nio/file/Glob.scala

@@ -280,7 +280,7 @@ object Glob {
   private object Root {
     implicit val ordering: Ordering[Root] = Ordering.by(_.root)
   }
-  private[file] final case object Empty extends RelativeGlob {
+  private[file] case object Empty extends RelativeGlob {
     override private[file] def matchers: List[RelativeGlob.Matcher] = Nil
     override def matches(path: Path): Boolean = false
   }