Currently the mouse cursor is shown by default and it can be
turned off by setting QT_QPA_EGLFS_HIDECURSOR to a non-zero
value. This is now enhanced with an automatic detection step
via QDeviceDiscovery (the helper the input code use anyway).
From now on if QT_QPA_EGLFS_HIDECURSOR is not set, the cursor
is shown only if a mouse device is present in the system.
This could later be enhanced further by showing and hiding the cursor
dynamically during runtime although that will not be of much use for
embedded platforms without libudev.
Change-Id: I7e4b85ea8807200871c88fc42b11ab2adac90d32
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
c16dbfbdde