When matching the locale's correct exponent separator, QLocale was
doing a case-insensitive match; but the Cyrillic fall-back was
matching case-sensitively, so failed to catch the case of lower-case e
and its Cyrillic equivalent, when used in a Cyrillic font in place of
the upper-case form of the other, where that's the locale's official
separator. So make this comparison case-insensitive.
Added some test-cases for the lower-case exponential separator.
Pick-to: 6.5
Fixes: QTBUG-113443
Change-Id: I18e22d7b3451fbb61e87d5b93661eadff3c7356e
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Ievgenii Meshcheriakov <ievgenii.meshcheriakov@qt.io>
4768fcf836