QQuickItem: avoid emitting signals during destruction

Origin: upstream, https://code.qt.io/cgit/qt/qtdeclarative.git/commit/?id=74873324bdf33997
Last-Update: 2023-02-26

If a QQuickItem is in the QQuickItem destructor, then it is both unsafe
and unnecessary to emit property change notifications. Connected code
can no longer rely on the state of the emitting object - if it was
originally a subclass of QQuickItem, then those subclass destructors
will already have run. And the QQuickItem destructor will also have
partially run, leaving the object in an undefined state.

Add a flag that we set to true at the top of ~QQuickItem, and don't emit
visibleChildrenChanged, parentChanged, visibleChanged, and
childrenChanged for items that are partially destroyed already.

[ChangeLog][Qt Quick][QQuickItem] QQuickItem no longer emits change
notifications for the parent, children, visible, and visibleChildren
properties while it is being destroyed.

Gbp-Pq: Name qquickitem_no_signals_on_destruction.patch

make tst_qmldiskcache::regenerateAfterChange() pass on big endian systems

Origin: upstream, https://code.qt.io/cgit/qt/qtdeclarative.git/commit/?id=dab0d62b655ce9a4
Last-Update: 2021-02-11

Gbp-Pq: Name tst_qmldiskcache_big_endian.patch

qtdeclarative-opensource-src (5.15.15+dfsg-3) unstable; urgency=medium

  * Backport upstream patch to fortify qmlExecuteDeferred some more.
  * Update debian/libqt5qml5.symbols from buildds’ logs.

[dgit import unpatched qtdeclarative-opensource-src 5.15.15+dfsg-3]

Import qtdeclarative-opensource-src_5.15.15+dfsg-3.debian.tar.xz

[dgit import tarball qtdeclarative-opensource-src 5.15.15+dfsg-3 qtdeclarative-opensource-src_5.15.15+dfsg-3.debian.tar.xz]

Import qtdeclarative-opensource-src_5.15.15+dfsg.orig.tar.xz

[dgit import orig qtdeclarative-opensource-src_5.15.15+dfsg.orig.tar.xz]