it is always used as __attribute__((...)).  Since variadic macros seem
to confuse poor doxygen, change it to a single-valued macro.

us to return proper PXE status codes, while simultaneously allowing for
more consistent error reporting (complete with verbose error messages as a
build-time option).

Remove compiler.h defines from osdep.h

easily from struct buffer.

refer to data outside of our data or stack segments.

addresses.  This will have to be reworked to use physical addresses thanks
to the PXE spec.