qtbase: set default platform plugin

Set the default platform plugin to be used, defaults based on
whether x11 and opengl are used.

recipes-qt/qt6/qtbase/0001-CMake-use-definitions-when-testing-EGL.patch

@@ -0,0 +1,24 @@
+From 1c1a22552ab587408d8c5775847e72891f698c90 Mon Sep 17 00:00:00 2001
+From: Samuli Piippo <samuli.piippo@qt.io>
+Date: Mon, 24 Aug 2020 11:10:17 +0300
+Subject: [PATCH] CMake: use definitions when testing EGL
+
+Use any definition from pkgconfig for the EGL compilation test.
+
+Change-Id: I95c659b87ab7b0de81f000e3f52195161a493ef5
+---
+ cmake/3rdparty/extra-cmake-modules/find-modules/FindEGL.cmake | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/cmake/3rdparty/extra-cmake-modules/find-modules/FindEGL.cmake b/cmake/3rdparty/extra-cmake-modules/find-modules/FindEGL.cmake
+index 55ca2a99bd..16dc1768ea 100644
+--- a/cmake/3rdparty/extra-cmake-modules/find-modules/FindEGL.cmake
++++ b/cmake/3rdparty/extra-cmake-modules/find-modules/FindEGL.cmake
+@@ -118,6 +118,7 @@ endif()
+ cmake_push_check_state(RESET)
+ list(APPEND CMAKE_REQUIRED_LIBRARIES "${EGL_LIBRARY}")
+ list(APPEND CMAKE_REQUIRED_INCLUDES "${EGL_INCLUDE_DIR}")
++list(APPEND CMAKE_REQUIRED_DEFINITIONS "${EGL_DEFINITIONS}")
+ 
+ check_cxx_source_compiles("
+ #include <EGL/egl.h>

recipes-qt/qt6/qtbase_git.bb

@@ -17,6 +17,7 @@ SRC_URI += "\
     file://0001-Add-linux-oe-g-platform.patch \
     file://0002-qlibraryinfo-allow-to-set-qt.conf-from-the-outside-u.patch \
     file://0005-Allow-build-without-opengl.patch \
+    file://0001-CMake-use-definitions-when-testing-EGL.patch \
 "
 
 DEPENDS += "\
@@ -57,6 +58,10 @@ BUILD_TYPE ?= "Release"
 # OpenSSL linking mode: runtime, linked
 OPENSSL_LINKING_MODE ?= "runtime"
 
+# Default platform plugin
+QT_QPA_DEFAULT_PLATFORM ?= "${@bb.utils.contains('DISTRO_FEATURES', 'x11', 'xcb', \
+    bb.utils.contains('DISTRO_FEATURES', 'opengl', 'eglfs', 'linuxfb', d), d)}"
+
 PACKAGECONFIG[cups] = "-DFEATURE_cups=ON,-DFEATURE_cups=OFF,cups"
 PACKAGECONFIG[dbus] = "-DFEATURE_dbus=ON,-DFEATURE_dbus=OFF,dbus"
 PACKAGECONFIG[udev] = "-DFEATURE_libudev=ON,-DFEATURE_libudev=OFF,udev"
@@ -108,6 +113,7 @@ EXTRA_OECMAKE += "\
 
 EXTRA_OECMAKE_append_class-target = "\
     -DFEATURE_rpath=OFF \
+    -DQT_QPA_DEFAULT_PLATFORM=${QT_QPA_DEFAULT_PLATFORM} \
 "
 
 SYSROOT_DIRS += "${prefix}/mkspecs"