Thanks for the info, I added `LIBSSL_STATIC_SRCPATH ?= /usr/lib/x86_64-linux-gnu/` in Makefile comments and reference to Makefile in the readme.
Glad to hear that both tlsa and ruxc are useful. Some old/stable distros _seem to be caught in between stable versions of libssl_ and sometime results in strange/faulty behaviour. Ubuntu 18:04 seems to be one of them, there were other reports on this tracker (eg., with mysql client lib and tls, iirc).
I am going to close this issue. Feel free to propose further enhancements/PRs to Makefile or docs to make it easier overall.