dropping legacy mock configs in next release

[Michael E Brown]

The next mock rpm release (0.7.2) will drop configs for RH 7.3/8/9 and
Fedora Core releases < 6.

These configs will remain in the git repository under etc/legacy/ for a
while yet. Will probably remove them on the next major release. Going
forward, policy for mock will be that we maintain mock configs for
currently supported operating systems.

If anybody else wishes to take over and release a 'mock-legacy-configs'
RPM, please let me know, as you are welcome to it. I'm sure that there
are people out there still using these configs, but I think that those
continuing to use these configs can probably maintain their own local
copy.
--
Michael