We can't just make a vfunc that takes a union of int
and pointer as argument, and then set up subclass-specific
action signals and signals that take int (in multifdsink's
case) or a GSocket * (in multisocketsink's case), and then
expect everything to Just Work. This blows up spectacularly
on PPC G4 for some reason.

Fixes multifdsink unit test on PPC, and fixes aborts in
multisocketunit test (now hangs in gst_pad_push - progress).