The new fields are added for program load in lib/bpf so
application uses api bpf_load_program_xattr() is able
to load program with btf and func_info data.

This functionality will be used in next patch
by bpf selftest test_btf.
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NMartin KaFai Lau <kafai@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>