Remove demos/tunala

This has been unmaintained for a long time. If it's still of interest
to anyone, it can be obtained easily enough by reverting this commit.
(It could join other demo code in some other repository, perhaps.) In
any case we don't want it taking up space in the baseline source
package, so <snip>.

Signed-off-by: Geoff Thorpe <geoff@openssl.org>