more flexible and allow older module versions to still work. Might not
be final code if we move over to DRI kernel module version, but will be
if we use XFree86 version. + Only build tdfx.o instead of tdfx-4_1_0.o
since tdfx.o has never changed its API.
- Fix old-style DMA for gamma driver (please test).
- Pull out IRQ handling into drm_dma.h (please test on i810, gamma).
- Lots of general cleanups, remove compiler warnings etc.