The documentation states that QDate::fromString() accepts negative
year numbers, but it did not. This patch adds support for negative
year numbers to QDate::fromString() and corresponding unit tests.
Furthermore, tests are added for positive signs (+) in date strings.
Fixes: QTBUG-84334
Task-number: QTBUG-84349
Change-Id: I575291e7b8317055d4bb530011d7b10c9cd37ae1
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
91140eb726