o Minor features (compilation):
    - Give an error message if trying to build with a version of LibreSSL
      known not to work with Tor.  (There's an incompatibility with
      LibreSSL versions 3.2.1 through 3.4.0 inclusive because of their
      incompatibility with OpenSSL 1.1.1's TLSv1.3 APIs.)
      Closes ticket 40511.