Return edata from non-"PA_REQUIRED" preauth types

Return edata from non-"PA_REQUIRED" preauth types

    * src/kdc/kdc_preauth.c (check_padata)
    Return e-data from any failing preauth module.
    Save the e-data and return value from the first failing module.
    If a subsequent module marked as PA_REQUIRED fails, return
    its e-data and error instead.

    * src/kdc/kdc_preauth.c (load_preauth_plugins)
    Quiet compiler warning by setting pointer to NULL.

ticket: new
Target_Version: 1.6
tags: pullup
Component: krb5-kdc

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@18895 dc483132-0cff-0310-8789-dd5450dbe970