* add "Platform" support inpmax/pmax/sysconf.c and pmax/include/sysconf.h
(based on Alpha cpuconf.[ch], with a namechange to avoid clashes with
support for models of MIPS cpus. They differ more than Alphas).
* For each supported model of DECstation, create a separate file
with the support for that model. Use model codenames, since
support is really baseboard-specific and CPU daugherboards can change.
Move code from machdep.c and pmax_trap.c,
Add sysconf (nee "cpuconf") support.
* Rename model-specific functions to match sysconf names.
* Clean up autoconf.c. Use platform callbacks.
* Retire pmax_trap.c.
Leaves I/O bus configuration and console configuration untouched.
jonathan