>I can see fairly arbitrary rules being "reasonable", depending on how
>rich a set of -m flags the compiler provides ...

You can get this now with `makeoptions'.  Simply
change an appropriate rule in Makefile.i386 from, e.g.,

	CC=	gcc2 ${WARN} ${DEBUG}

to:

	CC=	gcc2 ${WARN} ${DEBUG} ${CCMFLAGS}

and then add:

	makeoptions	CCMFLAGS="-m486"

Of course, you may have to remember to change the -mXXX when
you change `options CYRIX686' or whatever.