Please do not remove Block level API

[GregSlazinski]

This API is not as well tested as our normal API, so we recommend not using it.
We will be removing it in a future version. If the normal API doesn't provide
the functionality you need, please open a GitHub issue.

Please do not remove, I am using this API, it's really useful.
(including ZSTD_compressBegin_advanced)

I have my own efficient streaming support in my game engine that uses those functions.

Thanks