A future change in lualoader may take some liberties with the
loader_conf_files in the name of efficiency; namely, it may start omitting
it from the loader environment entirely so that it doesn't need to worry
about maintaining any specific value.
This variable has historically been incredibly volatile anyways, as it may
get set to completely different values in any given configuration file to
trigger a load of more files.
Document now that we may not maintain it in the future, but perhaps we'll
reserve the right to change our minds and eventually formally export all of
the loader configuration files that were read using this variable.
MFC after: 3 days
80a623bf52