libbpf: Fix compilation warning due to mismatched printf format

On ppc64le architecture __s64 is long int and requires %ld. Cast to
ssize_t and use %zd to avoid architecture-specific specifiers.

Fixes: 4172843e ("libbpf: Fix signedness bug in btf_dump_array_data()")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220209063909.1268319-1-andrii@kernel.org

tools/lib/bpf/btf_dump.c

@@ -1869,7 +1869,8 @@ static int btf_dump_array_data(struct btf_dump *d,
 	elem_type = skip_mods_and_typedefs(d->btf, elem_type_id, NULL);
 	elem_size = btf__resolve_size(d->btf, elem_type_id);
 	if (elem_size <= 0) {
-		pr_warn("unexpected elem size %lld for array type [%u]\n", elem_size, id);
+		pr_warn("unexpected elem size %zd for array type [%u]\n",
+			(ssize_t)elem_size, id);
 		return -EINVAL;
 	}