This may become useful for the ARM port if we want something like
writembr to include an u-boot image to put on install media. Until then,
haikuports is just a convenient way to store my patches.
x86_64 is used as a baseline: the "x86_64" entry, whatever status it has,
is transformed into "all", and then the other entries in ARCHITECTURES
either dropped or rearranged appropriately.