[mod_authn_gssapi] 500 if fail to delegate creds (#2967)
[mod_authn_gssapi] 500 if fail to delegate creds (#2967)

x-ref:
  "mod_authn_gssapi requires delegation?"
  https://redmine.lighttpd.net/issues/2967

lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4