According to the MPRIS specification, the Position property of the
Player object must be an int64.

dbus microsecond position overflows the unsigned 32-bit integer at
about 35:48 into a track's playback.  A 64-bit integer still means
an overflow, but after more than 292000 years into a track's playback.
Signed-off-by: Mirsal Ennaime <mirsal@videolan.org>
(cherry picked from commit 7531cecf)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>