bpf: Count stats for kprobe_multi programs

Adding support to gather missed stats for kprobe_multi
programs due to bpf_prog_active protection.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Song Liu <song@kernel.org>
Reviewed-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20230920213145.1941596-2-jolsa@kernel.org