SSL: removed OPENSSL_NO_SHA256 support. In OpenSSL itself, support for builds without SHA256 was removed in OpenSSL 1.1.0 and was already broken at that time (see https://github.com/openssl/openssl/commit/474e469bbd for details). In BoringSSL, support for OPENSSL_NO_SHA256 was removed in 2014. In LibreSSL as of 3.9.2, some support it still present, but broken.