tell nothing in the acorn32 port was using this version of
MEMORY_DISK_SIZE but I've left the code here incase the portmaster
wants it.
* rename MINIROOTSIZE to MEMORY_DISK_SIZE, so that all md(4) options
are consistently named
* fold opt_mdsize.h into opt_md.h
The IOMD/VIDC combination is now moved to arch/arm/iomd together. These
files still need a lot of cleaning up :( .... esp. the RC7500 support that
is still dormant in it; this needs either to be removed or split out for
RC7500's ``VIDC'' video/audio variant.
Apart from the RC7500 support wich is still in arch/arm32 the
iomd,vidc,riscpc and podulebus subdirectories of arch/arm32 can be removed.
This split still uses some small parts of arch/arm32 .... those are the MI
parts that haven't been moved yet.
RiscPC/A7000 have been tested and confirmed to build as should NC.