[PATCH] Fix invalid pointer return with QGridLayout::itemAt(-1)

QGridLayout::takeAt() and QLayoutItem *itemAt() only check the upper bound.
If the index < 0, these function will return invalid pointer.

Fixes: QTBUG-91261
Pick-to: 5.15 6.0 6.1
Change-Id: Idfb9fb6228b9707f817353b04974da16205a835c
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Gbp-Pq: Name fix-invalid-pointer-return-with-QGridLayout.diff

adjust QMimeDatabase implementation

Origin: upstream, https://code.qt.io/cgit/qt/qtbase.git/commit/?id=0cbbba2aa5b47224
Last-Update: 2021-05-18

When multiple globs match, and the result from magic sniffing is
unrelated to any of those globs, globs have priority and one of them
should be picked up.

This change also optimizes QMimeBinaryProvider::addFileNameMatches
to have the same logic as xdgmime for glob matching:
literals > extensions > other globs
As soon as one category matches, we can stop there.
This makes no difference in the overall results, in practice.

Gbp-Pq: Name mime_globs.diff

fix allocated memory of QByteArray returned by QIODevice::readLine

Origin: upstream, https://code.qt.io/cgit/qt/qtbase.git/commit/?id=6485b6d45ad165cf
Last-Update: 2021-02-20

Gbp-Pq: Name qiodevice_readline_memory.diff

include <limits> to fix some GCC 11 build issues

Origin: upstream, commits:
 https://code.qt.io/cgit/qt/qtbase.git/commit/?id=813a928c7c3cf986
 https://code.qt.io/cgit/qt/qtbase.git/commit/?id=9c56d4da2ff631a8
Last-Update: 2021-01-26

Gbp-Pq: Name gcc_11_limits.diff

QNAM: work around QObject finicky orphan cleanup details

Origin: upstream, https://code.qt.io/cgit/qt/qtbase.git/commit/?id=0807f16eb407eaf8
Last-Update: 2021-01-26

Gbp-Pq: Name qnam_connect_memory_leak.diff

Avoid use-after-free in QXcbConnection::initializeScreens()

Origin: upstream, https://code.qt.io/cgit/qt/qtbase.git/commit/?id=86b8c5c3f32c2457
Last-Update: 2020-11-23

Gbp-Pq: Name xcb_screens_uaf.patch

qtbase-opensource-src (5.15.2+dfsg-7) unstable; urgency=medium

  [ Lu Yaning ]
  * Backport upstream patch to fix invalid pointer return with
    QGridLayout::itemAt(-1): fix-invalid-pointer-return-with-QGridLayout.diff

[dgit import unpatched qtbase-opensource-src 5.15.2+dfsg-7]

Import qtbase-opensource-src_5.15.2+dfsg-7.debian.tar.xz

[dgit import tarball qtbase-opensource-src 5.15.2+dfsg-7 qtbase-opensource-src_5.15.2+dfsg-7.debian.tar.xz]

Import qtbase-opensource-src_5.15.2+dfsg.orig.tar.xz

[dgit import orig qtbase-opensource-src_5.15.2+dfsg.orig.tar.xz]