Revision 1728969

Add support for OpenSSL 1.1.0:
- Switch configure test for OpenSSL libcrypto
  from BN_init() to BN_new().
  - BN_init() is gone in OpenSSL 1.1.0.
    BN_new() exists at least since 0.9.8.
- use OPENSSL_malloc_init() instead of
  CRYPTO_malloc_init
- make cipherCtx a pointer. Type EVP_CIPHER_CTX
  is now opaque.
  - use EVP_CIPHER_CTX_new() in init() functions
    if initialised flag is not set (and set flag)
  - use EVP_CIPHER_CTX_free() in cleanup function
- Improve reuse cleanup
  - call EVP_CIPHER_CTX_reset() resp.
    EVP_CIPHER_CTX_cleanup() in finish functions
  - call EVP_CIPHER_CTX_reset() resp.
    EVP_CIPHER_CTX_cleanup() when Update fails
Backport of r1728958 and r1728963 from trunk.