A couple of questions about the new build system

[Phil Race]

1. Why do we have both --with-cups and --with-cups-include ?
All we use is the header files so the latter is what matters and
I'm not sure which one the build system prefers if both are set.

2. In the old build I could do
    cd make/sun/font
    make clean
    make all

Is there anything analagous to 'make clean' here,where I can have a 
level of comfort
that all generated files related to building just a particular area are 
removed.
This was useful after I touched a header file.
Now when I touch a header file, the new build system doesn't notice,
so I have to manually purge, but  nor does it (as far as I can see) give me
a target to purge that component. To do this I need to go hunt down
the directory with the object files and remove them.
Is there something better I can do ?

-phil.