You appear to be building with OpenSSL 1.1. OpenSSH upstream doesn't support this yet, and the Debian build-dependencies already account for this ("libssl1.0-dev | libssl-dev (<< 1.1.0~)"), so I think you must be attempting to build without the build-dependencies properly satisfied.
参见这个帖子:
https://bugs.debian.org/cgi-b...
里面有这么一段回复:
OpenSSH暂时还不支持OpenSSL 1.1。