Fixup demo exit status magic numbers

Fixup demo exit status magic numbers

The demo code is quite often block copied for new demos,
so this PR changes demos to use EXIT_SUCCESS & EXIT_FAILURE
instead of using 0 and 1.
Internal functions use the normal notation of 0 = error, 1 = success,
but the value returned by main() must use EXIT_SUCCESS and EXIT_FAILURE.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20545)