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-3) unstable; urgency=medium

  * Backport upstream patch to fix memory leak in QNetworkAccessManager
    from QMetaObjectPrivate::connect.
  * Backport upstream changes to add #include <limits> for GCC 11.
  * Update debian/watch: use format 4, and track only 5.15.x releases.
  * Update debian/libqt5core5a.symbols for hurd-i386.

[dgit import unpatched qtbase-opensource-src 5.15.2+dfsg-3]

Import qtbase-opensource-src_5.15.2+dfsg-3.debian.tar.xz

[dgit import tarball qtbase-opensource-src 5.15.2+dfsg-3 qtbase-opensource-src_5.15.2+dfsg-3.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]