[perl #121226] Please implement Unicode Corrigendum #9 (noncharacters)

Regardless of what the ultimate disposition of this is, I have attached a patch that would clarify the current situation for at least 5.20.  Any objections to it?

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via perlbug:  queue: perl5 status: open
https://rt.perl.org/Ticket/Display.html?id=121226

• [perl #121226] Please implement Unicode Corrigendum #9 (noncharacters) by Karl Williamson via RT
• Re: [perl #121226] Please implement Unicode Corrigendum #9(noncharacters) by Ricardo Signes