Merge branch 'likely-unlikely-for-bpf_helpers-and-a-small-comment-fix'

Anton Protopopov says:

====================
likely/unlikely for bpf_helpers and a small comment fix

These two commits fix a comment describing bpf_attr in <linux/bpf.h>
and add likely/unlikely macros to <bph/bpf_helpers.h> to be consumed
by selftests and, later, by the static_branch_likely/unlikely macros.

v1 -> v2:
  * squash libbpf and selftests fixes into one patch (Andrii)
====================

Link: https://patch.msgid.link/20250331203618.1973691-1-a.s.protopopov@gmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>