FindBoost unable to find libraries built by b2 with g++-7 using --layout=versioned

I tried to build my project with boost 1.66 (built by b2 with g++-7 using --layout=versioned) on Ubuntu 14.04, but FindBoost.cmake could not find the libraries because of the architecture tag. That's because the CMAKE_CXX_COMPILER_ARCHITECTURE_ID variable is not set for this compiler. I modified FindBoost to try CMAKE_LIBRARY_ARCHITECTURE and it worked for me (see attached). CMAKE_LIBRARY_ARCHITECTURE does not seem to be set for Visual C++, so this is not a replacement for CMAKE_CXX_COMPILER_ARCHITECTURE_ID. I don't have easy access to other compilers/platforms.