Remove old unused and unmaintained demonstration code.

Reviewed-by: Dr. Stephen Henson <steve@openssl.org>
"EC_POINT_invert" was checking "dbl" function pointer instead of "invert".

PR#2569

Reviewed-by: Rich Salz <rsalz@openssl.org>
CHANGES: mention new platforms.

Reviewed-by: Dr. Stephen Henson <steve@openssl.org>
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>
Don't call setenv in gost2814789t.c

The call to setenv in gost2814789t.c is not portable and may
not reflect the location of the GOST ENGINE on all platforms anyway.
Instead set OPENSSL_ENGINES in test/Makefile
Reviewed-by: Geoff Thorpe <geoff@openssl.org>
Add conditional unit testing interface.

Don't call internal functions directly call them through
SSL_test_functions(). This also makes unit testing work on
Windows and platforms that don't export internal functions
from shared libraries.

By default unit testing is not enabled: it requires the compile
time option "enable-unit-test".
Reviewed-by: Geoff Thorpe <geoff@openssl.org>