tools/mpris-player: Fix crash on 32-bit machines

tools/mpris-player: Fix crash on 32-bit machines

Invalid read of size 4
   at 0x424997E4: _dbus_header_get_byte_order (dbus-marshal-header.c:178)
   by 0x4249EAF7: _dbus_message_iter_check (dbus-message.c:731)
   by 0x4249FCAB: dbus_message_iter_next (dbus-message.c:2040)
   by 0x8053BE0: parse_properties.isra.8 (mpris-player.c:447)
   by 0x8054055: add_player (mpris-player.c:592)
   by 0x8054A49: proxy_added (mpris-player.c:801)
   by 0x804F6A5: parse_interfaces.part.3 (client.c:878)
   by 0x8050551: get_managed_objects_reply (client.c:888)
   by 0x424A6621: _dbus_pending_call_complete (dbus-pending-call.c:223)
   by 0x42491617: complete_pending_call_and_unlock (dbus-connection.c:2314)
   by 0x42494D3E: dbus_connection_dispatch (dbus-connection.c:4580)
   by 0x804AF57: message_dispatch (mainloop.c:76)
 Address 0x3ff00004 is not stack'd, malloc'd or (recently) free'd