hiawatha: fix bug #5276 and bump to version 8.4

Fix bug #5276 by disabling IPv6 when the toolchain lacks it.
It builds fine even if it's enabled but it probably doesn't work fine.

Also bump to version 8.4:
* MaxServerLoad option added.
* Bugfix: invalid reverse proxy request when URL parameters are present.
* PolarSSL updated to version 1.1.4.
* Small bugfixes and improvements.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>