The references to xgifb are clearly hold-overs from the SiS driver.
It should be clear that the places the refered to "xgifb" actually
meant "sisfb". Note the reference to 2.4 kernels. :)
Many, many unused structure fields were deleted. Many more were
documented as probably unused. Most of this is cruft left around from
the old SiS driver.
There are a number of XF86_VERSION_CURRENT tests in the code the
pre-date the XFree86 / X.org schism. All of these tests (and the
older versions of the code) have been removed.
Make sure that every C file includes config.h. Make sure that all
extension header files (e.g., Xv.h) come from X11/extensions. Remove
all of the $XFree86$ cruft.
Shuffle files around into their correct places. Create Makefile.am,
configure.ac, and autogen.sh based on similar files in other drivers. Delete
pre-modular files (e.g., Imakefile) that are no longer necessary.