Generating CPU family headers for multiple isas

[Ben Elliston]

   Right, but it's virtual, so no hardware struct elements would be
   emitted for it anyway.  What about the non-virtual ones?  Is there
   much point emitting them into isa-segregated hardware structs.

I understand what you're hinting at now, and I think it's correct.  There is
now no non-virtual "thumb"-specific hardware in my description.

The next step involves the large set of sfmt_ structures in union sem_format
in cpu.h, m'kay?  There are duplicates here, where isas share instruction
names.  Fortunately, C scoping rules eliminate the problem whereby the sfmt_
structure members share names (ie. f_rn).

Ben