* Add test case for OpenSSLs capability to init a evp context partially in several calls.
* EVP handling of CHACHA20_POLY1305 improvment
- save key at ctx for Init()s without IV
- reuse stored key for Init()s with new IV, reusing ctx
- free and zero key on ctx clenaup
* Adding type cast to XMALLOC to force compiler compatibility.
* EVP: using same DYNAMIC_TYPE in alloc and free of chacha20_poly1305 key.
Co-authored-by: Stefan Eissing <stefan.eissing@greenbytes.de>