Per https://bugzilla.redhat.com//show_bug.cgi?id=796430
switch the cache dir to be relative to runtimedir.

--- mod_auth_kerb-5.4/src/mod_auth_kerb.c.cachedir
+++ mod_auth_kerb-5.4/src/mod_auth_kerb.c
@@ -891,7 +891,10 @@ create_krb5_ccache(krb5_context kcontext
    int ret;
    krb5_ccache tmp_ccache = NULL;
 
-   ccname = apr_psprintf(r->connection->pool, "FILE:%s/krb5cc_apache_XXXXXX", P_tmpdir);
+   ccname = apr_pstrcat(r->connection->pool, "FILE:",
+                        ap_server_root_relative(r->pool, 
+                                                DEFAULT_REL_RUNTIMEDIR
+                                                "/krb5cc_apache_XXXXXX"));
    fd = mkstemp(ccname + strlen("FILE:"));
    if (fd < 0) {
       log_rerror(APLOG_MARK, APLOG_ERR, 0, r,