[perl #113094] Keeping track of 'Unescaped left brace in regex is deprecated'

The ExtUtils-MakeMaker and DB warnings reported by Reini Urban are still
present in 5.17.2. The former is also
https://rt.cpan.org/Ticket/Display.html?id=77468

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via perlbug:  queue: perl5 status: open
https://rt.perl.org:443/rt3/Ticket/Display.html?id=113094

• [perl #113094] Keeping track of 'Unescaped left brace in regex is deprecated' by Tom Wyant via RT
• Re: [perl #113094] Keeping track of 'Unescaped left brace in regexis deprecated' by Robin Barker
• [perl #113094] Keeping track of 'Unescaped left brace in regex is deprecated' by Tom Wyant via RT