Fixing RT #41141 -- handling carriage return after c-indicator.

This is a fix for https://rt.cpan.org/Public/Bug/Display.html?id=41141, which I ran into at work today. Basically

    YAML::Syck::Dump({ test => "?\r"})

produced some invalid YAML, which took down my daemons when I tried decoding the data later.

Let me know if I did something wrong (I skimmed through http://yaml.org/spec/1.2/spec.html, but I'm hardly an expert), or if there's something more you need me to do before accepting the pull request.

Cheers!