Merge remote-tracking branch 'tor-gitlab/mr/487' into maint-0.3.5

  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.

   [ AC_MSG_RESULT([no]) ],

   [ AC_MSG_ERROR([OpenSSL is too old. We require 1.0.1 or later. You can specify a path to a newer one with --with-openssl-dir.]) ])

AC_MSG_CHECKING([whether LibreSSL TLS 1.3 APIs are busted])

AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[

#include <openssl/opensslv.h>

#if defined(LIBRESSL_VERSION_NUMBER) && \

     LIBRESSL_VERSION_NUMBER >= 0x3020100fL && \

     LIBRESSL_VERSION_NUMBER < 0x3040100fL

#error "oh no"

#endif

   ]], [[]])],

   [ AC_MSG_RESULT([no]) ],

   [ AC_MSG_ERROR([This version of LibreSSL won't work with Tor. Please upgrade to LibreSSL 3.4.1 or later. (Or downgrade to 3.2.0 if you really must.)]) ])

AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[

#include <openssl/opensslv.h>

#include <openssl/evp.h>