[Bug c/84500] diagnostic says "array of chars" for arrays of wchar_t, char16_t and char32_t

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84500

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Saying "chars" implies narrow characters. The standard uses "character array"
for the general case.