Add a spec to confirm that Errno::EAGAIN is used for EWOULDBLOCK when appropriate
user
```ruby
require File.expand_path('../../../spec_helper', __FILE__)

describe "Errno::EAGAIN" do
  # From http://jira.codehaus.org/browse/JRUBY-4747
  it "is the same class as Errno::EWOULDBLOCK if they represent the same errno value" do
    if Errno::EAGAIN::Errno == Errno::EWOULDBLOCK::Errno
      Errno::EAGAIN.should == Errno::EWOULDBLOCK
    else
      Errno::EAGAIN.should_not == Errno::EWOULDBLOCK
    end
  end
end
```
assistant