The name CET is locale-dependent; but QLocale doesn't know about
localization of time zone names. Such abbreviated zone names are, in
any case, potentially ambiguous - various zones around the world have
collisions - so they can't be relied on.
QTimeZone's various backends have differing handlings of how to
abbreviate zone names (MS's provides no abbreviated names at all); and
it appears macOS actually follows the relevant localizations.
So it is hopeless to hard-code the expected zone abbreviations.
Changed the tests to consult QTimeZone for the abbreviation and
compare what it gets with the results of checks which should match
this. This is less stringent, but it is at least robustly correct,
thereby getting rid of assorted kludges and #if-ery.
Pick-to: 5.15
Task-number: QTBUG-70149
Change-Id: I0c565de3fd8b5987c8f5a3f785ebd8f6e941e055
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
449b347644