Since Zlib::GzipReader does not work in JRuby, the test is skipped.

## Why?

```
$ irb -rzlib
irb(main):001:0> f = Zlib::GzipReader.open('./test/data/LostineRiver.kml.gz', encoding: 'utf-8')
irb(main):002:0> f.readline('<')
(irb):2:in `evaluate': `readline': wrong number of arguments (given 1, expected 0) (ArgumentError)
	from org/jruby/RubyKernel.java:1277:in `eval'
	from org/jruby/RubyKernel.java:1725:in `loop'
	from org/jruby/RubyKernel.java:1426:in `catch'
	from org/jruby/RubyKernel.java:1426:in `catch'
	from /Users/naitoh/.rbenv/versions/jruby-9.4.11.0/lib/ruby/gems/shared/gems/irb-1.4.2/exe/irb:11:in `<main>'
	from org/jruby/RubyKernel.java:1223:in `load'
	from /Users/naitoh/.rbenv/versions/jruby-9.4.11.0/bin/irb:25:in `<main>'
```

Author: naitoh

test/test_order.rb

@@ -47,6 +47,8 @@ def test_order
      end
      # Provided by Tom Talbott
      def test_more_ordering
+       omit("not supported on JRuby") if RUBY_ENGINE == "jruby"
+
        doc = Zlib::GzipReader.open(fixture_path('LostineRiver.kml.gz'), encoding: 'utf-8') do |f|
          REXML::Document.new(f)
        end