Hard code cipher when ENGINIO_VALGRIND_DEBUG is set

Valgrind do not like openssl implementation of AES. The stderr is
spammed massively by warnings caused by usage of red zone, which makes
the analysis completely unusable.

Change-Id: I987434afbfc810c8b4347afbf2204dd4c3ba44ef
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>