Check the return code from ASN1_TIME_diff()
Check the return code from ASN1_TIME_diff()

The function can fail so we should check the return code.

Found by Coverity

Reviewed-by: Bernd Edlinger <ac6902843ae77cc0d49b9c8ddec4cbf141db1bb7@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/5339)

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