Don't check for time() failing in CT_POLICY_EVAL_CTX_new

See https://github.com/openssl/openssl/pull/1554#issuecomment-246354677

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Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1554)