examples/ct: add convenience local var
examples/ct: add convenience local var

google/certificate-transparency-go,google/certificate-transparency-go,RJPercival/certificate-transparency-go,daviddrysdale/certificate-transparency-go,google/certificate-transparency-go,RJPercival/certificate-transparency-go,daviddrysdale/certificate-transparency-go,RJPercival/certificate-transparency-go,daviddrysdale/certificate-transparency-go