Fixed visibility of Scanner.Visitor.

Must be package private because it uses TimeNSize
in method signatures, that is also package private.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>

jetty-util/src/main/java/org/eclipse/jetty/util/Scanner.java

@@ -153,7 +153,7 @@ public class Scanner extends AbstractLifeCycle
      * A FileVisitor for walking a subtree of paths. The Scanner uses
      * this to examine the dirs and files it has been asked to scan.
      */
-    public class Visitor implements FileVisitor<Path>
+    class Visitor implements FileVisitor<Path>
     {
         Map<String, TimeNSize> scanInfoMap;
         IncludeExcludeSet<PathMatcher,Path> rootIncludesExcludes;