Merge branch 'bpf-zero-hash-seed'

Lorenz Bauer says:

====================
Allow forcing the seed of a hash table to zero, for deterministic
execution during benchmarking and testing.

Changes from v2:
* Change ordering of BPF_F_ZERO_SEED in linux/bpf.h

Comments adressed from v1:
* Add comment to discourage production use to linux/bpf.h
* Require CAP_SYS_ADMIN
====================

Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>