mock buildroot definitions

[Florian La Roche]

> no the concern is that format for the comps.xml has changed and may
> change in the future and it matters what version of yum you use with
> what comps.xml format.

You might want to just extend the code to also read newer versions,
but keep also reading the old ones. Not a real good solution to
comps format changes, but at least we would get new things in without
moving to yet another file/format.

regards,

Florian La Roche