How "official" is libressl support in High Sierra?

I am trying to port an OpenSSL-based C program from Linux to macOS, and I would like to use a library for TLS which is officially supported by the OS, because then the OS keeps that library up-to-date and secure without any extra work for me or the user of my application. I though LibreSSL was officially supported in macOS and I have already ported my program have a LibreSSL backend, but I'm unsure of the state of LibreSSL within macOS. Is there any official documentation that addresses whether developers should treat the LibreSSL library as depricated or not? PS: I've searched on Apple's developer site, but the [official Apple documentation](https://developer.apple.com/library/content/documentation/Security/Conceptual/cryptoservices/SecureNetworkCommunicationAPIs/SecureNetworkCommunicationAPIs.html) about encrypting network communication makes ABSOLUTELY NO mention of LibreSSL (which is not the same as OpenSSL).