Pagesize no longer matters in architecture decisions, the entire cache file
is mmaped into the library. However, lots of intptr_t values are in use now,
so that value is important.
fc-lang now requires fcserialize.c, which has been added to the repository.
Map existing architecture signature to short architecture name
at build time. This architecture name is (as yet) unused, but will be used
to build per-architecture cache files with names made unique by including
the architecture name. The auto-detected architecture name can be overridden
with the --with-arch=ARCH configure option.