Changelog:
===========
- remove unnecessary struct_ops prog validity check
- handle yet another corner case of nulling out struct_ops program
- fix libbpf_strerror_r() handling unknown errors
- libbpf: improve early detection of doomed-to-fail BPF program loading
Signed-off-by: Wang Mingyu <wangmy@fujitsu.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>