package/mesa3d: If udev is not present, sysfs is used as a replacement

Support for sysfs as a replacement for udev was added 2014/05/30:
http://cgit.freedesktop.org/mesa/mesa/commit/configure.ac?id=85b6f36ca5238dd3fec7c5fcacb8b7074ce53c8e



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>