libbpf: Add bpf_link_create support for multi uprobes

Adding new uprobe_multi struct to bpf_link_create_opts object
to pass multiple uprobe data to link_create attr uapi.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-14-jolsa@kernel.org


Signed-off-by: Alexei Starovoitov <ast@kernel.org>