i386, amd64 will be moved into an arch/ subdirectory

[Matthew Dillon]

    I might get this in earlier then I thought.  The changes aren't too
    hard to implement.

    The make buildkernel stuff will work pretty much as it did before.
    People who manually cd into the object tree and type 'make' will
    have to cd into a different place once I commit the work, e.g.
    instead of /usr/obj/usr/src/sys/i386/conf you would cd into
    /usr/obj/usr/src/sys/config/.

						-Matt