Change EVP_CIPHER_CTX_iv_length() to return current ivlen for some modes

Note a flag needed to be added since some ssl tests fail if they output any error
(even if the error is ignored). Only ciphers that handle the GET_IV_LEN control set this flag.

Fixes #8330

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9499)