If AuthorizedPrincipalsCommand is specified, however

If AuthorizedPrincipalsCommand is specified, however
AuthorizedPrincipalsFile is not (or is set to "none"), authentication will
potentially fail due to key_cert_check_authority() failing to locate a
principal that matches the username, even though an authorized principal
has already been matched in the output of the subprocess. Fix this by using
the same logic to determine if pw->pw_name should be passed, as is used to
determine if a authorized principal must be matched earlier on.

ok djm@