asn1: merge upstream Go 1.12 changes
asn1: merge upstream Go 1.12 changes

Pulls in the following upstream commit that affects ./asn1/:

 - 3813edf26edb all: use "reports whether" consistently in the few places that didn't

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