follow-up to 9d837f19 "Upgrade to Boost 1.65.1",
in accordance with <https://github.com/boostorg/config/commit/
2dfd1a95bab49afcc374aadb1491d8fde189db74> "Move workaround.hpp out of detail
(used by more than Config)"

Change-Id: I666911ef89e94b4ab717c23394b76dd0662dd9ef
Reviewed-on: https://gerrit.libreoffice.org/42443Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>