bpf: update BPF_MAP_CREATE decoding

bpf: update BPF_MAP_CREATE decoding

Implement decoding of union bpf_attr.numa_node field for BPF_MAP_CREATE
command introduced by linux kernel commit v4.14-rc1~130^2~196^2~1.

* configure.ac: Check for numa_node member of union bpf_attr
instead of inner_map_fd.
(decode_BPF_MAP_CREATE): Add numa_node field to the structure, print it.
* NEWS: Mention this.
* tests/bpf.c: Update macro guards of BPF_MAP_CREATE decoder test.
(init_BPF_MAP_CREATE_first, print_BPF_MAP_CREATE_attr): Update expected
output.
(init_BPF_MAP_CREATE_attr): Initialize numa_node field, update offset.