To use:

1. Include boost-fallback.cmake in your project
2. If desired, use the provided header file to switch between the various implementations:

include(boost-fallback/boost-fallback.cmake)

set(NAMESPACE_ALIAS some_namespace)
configure_file(boost-fallback/boost-std-configuration.h.cmake
    boost-fallback/boost-std-configuration.h)
target_include_directories( executable-name PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/boost-fallback )