netsniff-ng: fix build with kernel headers v4.10+

Add upstream patch removing use of GENL_ID_GENERATE that was dropped in kernel
version 4.10.

Fixes:
http://autobuild.buildroot.net/results/58d/58d7809cae739f728c58291f2111684d6c0578f3/
http://autobuild.buildroot.net/results/65c/65ce9807116ca70908e0aabae59a36c7774dfa7a/
http://autobuild.buildroot.net/results/64b/64b3f8af2ebc5a14ecbef72039ef527b5d71f12c/



Cc: Joris Lijssens <joris.lijssens@gmail.com>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>