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-2) unstable; urgency=medium

  [ Alexander Volkov ]
  * Backport upstream patch xcb_screens_uaf.patch in order to fix
    use-after-free in the xcb plugin.

  [ Dmitry Shachnev ]
  * Build with libxcb-util-dev 0.4.0 which Debian now has.
    - Drop loosen_xcb-util_requirement.diff, no longer needed.
  * Bump Standards-Version to 4.5.1, no changes needed.
  * Upload to unstable.

  [ Lisandro Damián Nicanor Pérez Meyer ]
  * Build the experimental XCB native painting engine. This has been disabled
    as a default by upstream, but our X2Go users do really benefit from it if
    they export QT_XCB_NATIVE_PAINTING (Closes: #976274).

[dgit import unpatched qtbase-opensource-src 5.15.2+dfsg-2]

Import qtbase-opensource-src_5.15.2+dfsg-2.debian.tar.xz

[dgit import tarball qtbase-opensource-src 5.15.2+dfsg-2 qtbase-opensource-src_5.15.2+dfsg-2.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]