CRAN has binaries for Windows and macOS. To build this on Linux/BSD-ish
systems, you need at least g++4.9 or clang++. This is a forced requirement
by the ndjson library.

The least painful way to do this is to install gcc >= 4.9 (and you should
install ccache while you're at it) and mmodfiy ~/.R/Makevars thusly:

    # Use whatever version of (g++ >=4.9 or clang++) that you downloaded
    VER=-4.9
    CC=ccache gcc$(VER)
    CXX=ccache g++$(VER)
    SHLIB_CXXLD=g++$(VER)
    FC=ccache gfortran
    F77=ccache gfortran