[SSSD] [PATCH] KRB5: Recover gracefully if the ccache file could not be reused

[Jakub Hrozek]

https://fedorahosted.org/sssd/ticket/1384

I tested by logging in from one terminal, then chowning the ccache to
root.root to make the existing ccache unusable by the krb5_child process
and attempting to log in from another terminal.

Without the patch, the second login would just fail. With the patch, the
second login would succeed so the user can su or sudo and fix the
permissions problem.