perlapi: Combine the UTF8SKIP entries into a single one

[khwilliamson]

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• [ ] This set of changes requires a perldelta entry, and it is included.
• [ ] This set of changes requires a perldelta entry, and I need help writing it.
• [x] This set of changes does not require a perldelta entry.

[tonycoz]

Fine except for the commit message