... in lieu of <cctype>'s toupper(), which is locale-dependent, and
out-of-line.
The code doesn't run into the toupper(i) issue in the Türkiye locale,
because we don't run tests in that locale and because 'i' is not a
valid format specifier, but don't let the next reader of the code
guess when the use of toAsciiUpper() provides unambiguous guidance.
Task-number: QTBUG-109235
Pick-to: 6.5
Change-Id: I8988f5190441e1ae5cb57370952cda70ca6bb658
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>