Comment (by Roland Haas):

Thank you. Indeed, VERBOSE=1, as shown on the webiste, does not work. The correct values is VERBOSE=yes. I have just corrected the website. If you could re-run with VERBOSE=yes and send the produced make.log file, that would be great. Sorry about the incorrect information on the website. Your env.log looks fine to me, so still no idea what is going on.

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Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2679/how-to-link-an-externally-compiled-library