Fix a crash in EVP_CIPHER_CTX_cleanup due to cipher_data may be NULL

or EVP_CTRL_INIT/EVP_CTRL_COPY was not called or failed.
- if that happens set cipher = NULL.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2149)