move ffb_fastfill_parms to ffb_accel_common.c so the EXA code can work
without XAA

include config.h #ifdef HAVE_CONFIG_H

partial port to xorg-server 1.18. both cg6 and ffb need more help.

- move some routines used by both XAA and EXA to their own file
- enable hardware prefetch when reading from video memory - now blits in EXA
are no longer slower than in XAA
- start fleshing out Xrender routines