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

Use %m to print error

directory.

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).

These don't yet take advantage of the buffer functionality.

Remove compiler.h defines from osdep.h