The attach() -> create() sequence was not covered by unit-tests in
qtbase, but this approach is used inside QSharedImageLoader.
It turns out that 02c42b26e1 broke this
usecase for legacy mode, and the create() triggered an assertion
in QSharedMemorySystemV::updateNativeKeyFile(). Fix it by clearing
the nativeKeyFile if ftok() call in QSharedMemorySystemV::handle()
fails().
Add unit-tests for the attach() -> create() scenario.
These tests revealed that this scenario fails also in non-legacy mode
for SystemV, so add QEXPECT_FAIL for these cases for now. This will
be addressed in a separate patch.
Pick-to: 6.6
Change-Id: If133fa56c82eba902374dc48d2757046b3d40baf
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>