bpf: Add missing return to resolve_btfids

int sets_patch(struct object *obj) doesn't have a 'return 0' at the end.

Fixes: fbbb68de ("bpf: Add resolve_btfids tool to resolve BTF IDs in ELF object")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200806155225.637202-1-sdf@google.com