load_key_certs_crls: Avoid reporting any spurious errors
load_key_certs_crls: Avoid reporting any spurious errors

When there is other PEM data in between certs the OSSL_STORE_load
returns NULL and reports error. Avoid printing that error unless
there was nothing read at all.

Fixes #15945

Reviewed-by: Paul Dale <ddec78389666b4f7c9b4d110380c848489a3e4aa@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15949)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl