Rivet build fails centos7

[maroozm]

Rivet build fails on centos7 and ubuntu 20 with a similar as on these links: https://alice-talk.web.cern.ch/t/configure-error-a-compiler-with-support-for-c-14-language-features-is-required/919 https://github.com/mapnik/mapnik/issues/4226 I dont know if the problem can be reproduced but the problem seems to be with the option: ${CXX11:+--enable-stdcxx11} As soon as I replace it with -fPIC. It compiles successfully.