check for it, expecting Imake to have defined it already. (Should be
replaced with more specific checks & defines, but there's too many to
get them all right now.)
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.