package/qt5base: fix build with TI SGX GL stack

package/qt5base: fix build with TI SGX GL stack

qt5base FTBFS with TI SGX GL stack because it defines a type that is
incompatible with that expected by Qt.

Fix that by adapting a mix of upstream bug reports, upstream tentative
patch, and various comments on various Qt forums, none of which were
satisfying for various reasons explained in each resource:

  - https://bugreports.qt.io/browse/QTBUG-72567
  - https://codereview.qt-project.org/c/qt/qtbase/+/248270
  - https://forum.qt.io/topic/88588/qtbase-compilation-error-with-device-linux-rasp-pi3-g-qeglfskmsgbmwindow-cpp/8
  - https://forum.qt.io/topic/91596/raspberry-pi-3-compiling-qt-5-11-0-problem/6
  - https://patchwork.ozlabs.org/project/buildroot/patch/20200702201125.3639873-1-aduskett@gmail.com/#2579598

... which, mixed together with my little understanding of Qt, GL, and
C++, gave a relatively simple patch that overcomes the build failure on
TI's SGX, while at the same time keeping buildability and functionality
on other platforms.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Adam Duskett <aduskett@gmail.com>
Cc: Markus <zehnder@live.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>