Use the new //crl/x509 library in the CA, to make handling the
ReasonCode of each CRL entry significantly easier. This also
allows us to log the reason code along with each serial in the
CRL.
Also, make a couple tiny tweaks to the //crl/x509 package that
were discovered to be useful while writing this change. These
include moving it to a //crl/crl_x509 directory so that it doesn't
have to be aliased at import time.
Fixes#6199
Aaron Gable