libbpf: use explicit map reuse flag to skip map creation steps

Instead of inferring whether map already point to previously
created/pinned BPF map (which user can specify with bpf_map__reuse_fd()) API),
use explicit map->reused flag that is set in such case.

Acked-by: Jiri Olsa <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: anakryiko

tools/lib/bpf/libbpf.c

@@ -5465,7 +5465,7 @@ bpf_object__create_maps(struct bpf_object *obj)
 			}
 		}
 
-		if (map->fd >= 0) {
+		if (map->reused) {
 			pr_debug("map '%s': skipping creation (preset fd=%d)\n",
 				 map->name, map->fd);
 		} else {