Fix the return value of OBJ_create

Fix the return value of OBJ_create

OBJ_create is supposed to return NID_undef on error
and the newly created NID on success.

Fixes: 88a1fbb8d1b2 ("reduce lock contention when adding objects to ADDED_OBJ hash table")
Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/28293)