Dist helper shell scripts.
Dist XAA.HOWTO and a few more unused C files.
Dist xorgconf.cpp.
Fix DIST_EXTRA typo.
Clean yacc and lex generated files only during make maintainer-clean as we
don't expect users to have those tools installed.
Fix the dri and drm build. Fix server-side DMX extension build. Make
xf4bpp use the correct version of mfbline.c for mfbseg.c. Add #ifndef
_HEADERNAME_H_/#define _HEADERNAME_H_/.../#endif to the headers.