Extend the chacha regress to cover the ChaCha interface, in addition to the
single-shot CRYPTO_chacha_20() interface (the ChaCha interface was already
tested via the EVP regress, but not extensively). The additional ChaCha
tests include single-shot writes, along with partial/single-byte writes
that currently fail due to a bug in the underlying implementation.
remove use of internally-deprecated OPENSSL_malloc/free
disable warnings about constant addresses in gcc 4.6 and later
do not include <openssl/modes.h>, modes_lcl.h already does