Add "quirks" for chisel

The idea is that Chisel doesn't map very well to this "one command per
file" layout that I've been using for the other toolchains.  I added a
"language_quirks" call that pretty much says "I've processed
everything pconfigure understands, let me do something weird".

This quirks call is used by the Chisel support module to tell make
that generating the Chisel binary also generates some ancillary code
(a header file that's used by the C++ support, for instance).

The Chisel support still isn't exactly what I'd call clean, but at
least it somewhat works :).