selftests/bpf: Test wire_len/gso_segs in BPF_PROG_TEST_RUN

Make sure we can pass arbitrary data in wire_len/gso_segs.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191213223028.161282-2-sdf@google.com