bpf: Sync bpf.h to tools

Sync include/uapi/linux/bpf.h with tools/

Changes
  v1->v2:
  - BPF_F_ADJ_ROOM_MASK moved, no longer in this commit
  v2->v3:
  - BPF_F_ADJ_ROOM_ENCAP_L3_MASK moved, no longer in this commit

Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>