The Zlib::GzipReader in JRuby does not behave as expected with REXML, so the test is skipped (#292)

## Why? JRuby's `Zlib::GzipReader#readline` does not support arguments, so when using `Zlib::GzipReader.open`, it always returns an empty string and does not function. We will temporarily exclude `Zlib::GzipReader` from test coverage. ``` $ test/run.rb --location test/test_order.rb:49 Failure: test_more_ordering(REXMLTests::OrderTester) /Users/naitoh/ghq/github.com/naitoh/rexml/test/test_order.rb:110:in `test_more_ordering' 107: count += 1 108: } 109: => 110: assert_equal( actual.size, count ) 111: end if defined?(Zlib::GzipReader) 112: end 113: end <46> expected but was <0> ``` See: jruby/jruby#8997

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
@@ -104,6 +106,8 @@ def test_more_ordering
  assert_equal( actual[count], n ) unless n =~ /Arrive at/
  count += 1
  }
+
+ assert_equal( actual.size, count )
  end if defined?(Zlib::GzipReader)
  end
 end