[9fans] maxround and stack frame sizes

[Anthony Martin]

I'm curious about the origins of the maxround
function in the compilers. Specifically, why is
5c different from all the others?

It seems the common implementation gives rise
to unnecessarily large stack frames.

For convenience:

    /sys/src/cmd/6c/swt.c:/^maxround
    /sys/src/cmd/5c/swt.c:/^maxround
    /sys/src/cmd/cc/dcl.c:/^adecl

Thanks,
  Anthony