libffi5 having "extra" priority

[Andreas Rottmann <a.rottmann@gmx.at>]

Hi!

I just checked my QA page and noticed this:

   Package is optional and has a Depends on libffi5 (>= 3.0.4) which is extra on mips.
   [... and for all other archs]

Is there a reason libffi5 has "extra" priority? It seems a relatively
"core" package, in the sense that other packages are quite likely to
depend on it, for example programming language interpreters (or
runtimes) offering an FFI. ATM, the following package are direct reverse
dependencies of libffi5, and are have a priority higher than "extra":

    % grep-available \( -F Depends libffi5 \) --and --not -F Priority extra \
      -s Package,Priority

    Package: libgwrap-runtime2
    Priority: optional

    Package: ghc6
    Priority: optional

    Package: python-gobject
    Priority: optional

    Package: xmonad
    Priority: optional

    Package: guile-g-wrap
    Priority: optional

    Package: haddock
    Priority: optional

Regards, Rotty