Dating from the origins of our support for the zoneinfo file format,
the mapping of POSIX's day-numbering (0 = Sunday through 6 = Saturday,
see [*]) to Qt's (1 = Monday through 7 = Sunday) was done by mapping 0
to 1, when it should have been 7.
[*] http://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
Corrected a QTimeZone test that trusted the results it got without
checking which day of the week those were: they were all Mondays.
Verified that the corrected dates are in fact Sundays.
Checked the zone abbreviations, too.
Fixes: QTBUG-90553
Pick-to: 6.0 5.15
Change-Id: I84b4b14f9892ff687918cd3c42c7c9807e45313c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
38a72af4fd