On svn-auth-x509 branch, restore some disabled output from auth command.

This does mean that svn.ssl.server entries created with 1.9.x versions
before this will output some spurious entries from when we wrote out
details about the certificate to the credential cache.

* subversion/svn/auth-cmd.c:
  (list_credential): Restore the reason the cert failed normal validation
    and the output of unknown keys.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/svn-auth-x509@1613538 13f79535-47bb-0310-9956-ffa450edef68