qt5base: correct eglfs support in qmake.conf.in

qt5base: correct eglfs support in qmake.conf.in

Setting EGLFS_DEVICE_INTEGRATION at the end of qmake.conf like is done
by commit 0c219ddb8a doesn't work correctly: it has to be set before the
include(../common/linux_device_post.conf)

Instead of appending to the file, change it into a qmake.conf.in
template file that contains a placeholder for the
EGLFS_DEVICE_INTEGRATION assignment and update it with sed. Since the
sed always has to be executed, this removes the need for a separate
QT5BASE_CONFIGURE_QMAKE_CONFIG definition.

Signed-off-by: Giulio Benetti <giulio.benetti@micronovasrl.com>
[Arnout: simplify the replacement, move sunxi-mali support to a
 separate patch]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>