Somewhere the 8c fixes for the switch selector were merged together
with other changes and no one has been able to extricate them so they
could be applied to 5c (et al.).
Um. No, that's not the problem. In fact, the changes were redone ages ago,
and most of the work is done by port, based on per-platform settings.
The platform must support OREGPAIR in some form, and 5c does not.
I have got a 5c that does vlongs, and thus OREGPAIR,
but it won't compile ghostscript yet, so it hasn't been released.