As announced in #1148038, new upstream releases of WebKitGTK no longer
support big-endian architectures.

e-d-s already has a list of architectures without WebKit. This list
needs to be extended to include all big-endian release architectures
(there is only one, s390x) and ideally also all big-endian -ports
architectures (hppa m68k powerpc ppc64 sparc64), so that we don't have
to remove all of e-d-s' libraries from the big-endian architectures,
which would be more disruptive.

    smcv