kmod : protect against architectures without __NR_finit_module

This bug caused udev to fail to load any module, crashing with Illegal
instruction.

The patch was taken from upstream and should be integrated in the next
version of kmod (version 14)

Signed-off-by: Jérémy Rosen <jeremy.rosen@openwide.fr>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>