mock buildroot definitions

[seth vidal]

Hey,
 So it was brought up a while ago that due to the changing nature of the
comps.xml format that we should not rely on it for the buildroot
installations in mock. The idea a while back was to just have a
'buildroot' rpm that required all the stuff that would normally be in
the comps.xml group. Then we could just install that rpm and it pulls in
the rest of the buildroot components.

What do folks think? Worth going through the process to do it?

-sv