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.
This ensures that a dependency like lib:libboost_x >= 1.63.0 will not
be fulfilled with the boost165 package for example, which contains
version specific library names that will not work for software built
against other versions.
waddlesplash