krb5_child: Warn if user cannot read krb5.conf
Attached patch should siplify troubleshoting of
issues with permission of krb5.conf. It's not clear from
krb5_child.log even with full debug level.
[sss_get_ccache_name_for_principal] (0x4000):
Location: [FILE:/tmp/krb5cc_12069_XXXXXX]
[sss_get_ccache_name_for_principal] (0x2000):
krb5_cc_cache_match failed: [-1765328243]
[Can't find client principal user@EXAMPLE.COM in cache collection]
[create_ccache] (0x0020): 735: [13][Permission denied]
Resolves:
https://fedorahosted.org/sssd/ticket/2931
Reviewed-by: Michal Židek <mzidek@redhat.com>
(cherry picked from commit 38f251e531b1c68e70eaa98dfecaf78da5f36ccc)