encoding/asn1: Improved control of flags and times
This change corrects the serialization of asn1.Flag values, so that
when set, they serialize to an empty value, and when unset, they are
omitted. It also adds a format parameter that allows calling code
to control whether time.Time values are serialized as UTCTime or
GeneralizedTime.
Change-Id: I6d97abf009ea317338dab30c80f35a2de7e07104
Reviewed-on: https://go-review.googlesource.com/5970
Reviewed-by: Adam Langley <agl@golang.org>
Run-TryBot: Adam Langley <agl@golang.org>