This bug was originally reported by Matthias Klose.

The zero build for architectures not explicitly listed fails currently in
hotspot, because of an unset macro, and the compiler complains about a single -D
option passed.

Here are two proposals how to fix these:

 - Not passing the -D<cpu_define> if it is not set. Afaik the define
   is only used for hotspot builds, not for zero builds.

 - Provide a fall back for "unknown" zero architectures.

Matthias