Fix incomplete check on X509V3_add1_i2d()

Fix incomplete check on X509V3_add1_i2d()

X509V3_add1_i2d() can return both -1 and 0 as an error code. This check
only checked for 0. Change it into <= 0 to also catch the -1 error code.

CLA: trivial

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20157)