The old whitelist was a leftover from the early days of YQ2. It should
run on most / all architectures, as long SDL supports them. As suggested
by smcv in issue #138 generate the OSTYPE and ARCH defines by the build
system instead of hardcoding it.
Savegame compatibility is provided by bumping the savegame version. Old
savegames are compared against the old OSTYPE and ARCH defined, new ones
against the new defines. This compatibility code should be removed
somewhere in the distant future.
