Find.find -> Use Dir.children instead of Dir.entries

Dir.children is available since Feature #11302.
Find.find can use of the new list (having no '.' neither '..' entries),
making now superflous an if statement.

This change can improve the performance of Find.find when the path
has lots of entries (thousands?).

https://bugs.ruby-lang.org/issues/11302
patched by Espartaco Palma <esparta@gmail.com>
https://github.com/ruby/ruby/pull/1697 fix GH-1697
[Feature #13896]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59926 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/find.rb

@@ -55,14 +55,13 @@ module Find
           end
           if s.directory? then
             begin
-              fs = Dir.entries(file, encoding: enc)
+              fs = Dir.children(file, encoding: enc)
             rescue Errno::ENOENT, Errno::EACCES, Errno::ENOTDIR, Errno::ELOOP, Errno::ENAMETOOLONG
               raise unless ignore_error
               next
             end
             fs.sort!
             fs.reverse_each {|f|
-              next if f == "." or f == ".."
               f = File.join(file, f)
               ps.unshift f.untaint
             }