Merge branch 'libbpf: rename bpf_prog_attach_xattr to bpf_prog_attach_opts'

Christy Lee says:

====================

All xattr APIs are being dropped, mark bpf_prog_attach_opts() as deprecated
and rename to bpf_prog_attach_xattr(). Replace all usages of the deprecated
function with the new function name.

  [0] Closes: https://github.com/libbpf/libbpf/issues/285

Changelog:
----------
v2 -> v3:
https://lore.kernel.org/all/20220106234639.1418484-2-christylee@fb.com/

* Fixed build break

v1 -> v2:
https://lore.kernel.org/all/20211230000110.1068538-1-christylee@fb.com/

* Used alias instead of returning original function
* Split out selftests to a different commit
====================

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>