libbpf: Fix pr_warn type warnings on 32bit

The printed value is ptrdiff_t and is formatted wiht %ld. This works on
64bit but produces a warning on 32bit. Fix the format specifier to %td.

Fixes: 67234743 ("libbpf: Generate loader program out of BPF ELF file.")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210604112448.32297-1-msuchanek@suse.de

tools/lib/bpf/libbpf.c

@@ -4581,7 +4581,7 @@ static int init_map_slots(struct bpf_object *obj, struct bpf_map *map)
 		targ_map = map->init_slots[i];
 		fd = bpf_map__fd(targ_map);
 		if (obj->gen_loader) {
-			pr_warn("// TODO map_update_elem: idx %ld key %d value==map_idx %ld\n",
+			pr_warn("// TODO map_update_elem: idx %td key %d value==map_idx %td\n",
 				map - obj->maps, i, targ_map - obj->maps);
 			return -ENOTSUP;
 		} else {
@@ -6205,7 +6205,7 @@ static int bpf_core_apply_relo(struct bpf_program *prog,
 		return -EINVAL;
 
 	if (prog->obj->gen_loader) {
-		pr_warn("// TODO core_relo: prog %ld insn[%d] %s %s kind %d\n",
+		pr_warn("// TODO core_relo: prog %td insn[%d] %s %s kind %d\n",
 			prog - prog->obj->programs, relo->insn_off / 8,
 			local_name, spec_str, relo->kind);
 		return -ENOTSUP;