Mark only for i386. xmms-quix3dn previously relied on compat4x failing on
amd64 but as compat4x now installs there if fails to detect 32 libs via
LIB_DEPENDS. While the failure has to do with compat4x port problems, this
port nevertheless installs i386 plugin which will not work with native
xmms on amd64 (and most probably not on alpha).
Reported by: kris