[18+] improve upgrade pre-check for Unicode updates - Mailing list pgsql-hackers

Patch attached.

When checking for expression indexes that may be affected by a Unicode
update during upgrade, check for a few more functions. Specifically,
check for documented regexp functions, as well as the new CASEFOLD()
function.

Also, fully-qualify pg_catalog references to the text type as well as
regtype.

Regards,
    Jeff Davis