Freeze exception for resolv.conf parser changes

[Florian Weimer]

On 06/30/2017 09:45 PM, Florian Weimer wrote:
> But I would like to continue working on this during the first week of
> the freeze.  I see the following five immediate improvements:
> 
> * More test coverage.  (I tested resolv.conf reloading only manually.)
> * Lazy allocation of the main state in resolv/resolv_conf.c, to conserve
>   data segment space for programs which do not use the stub resolver.
> * Use a free list for indexes into the resolv_conf array (speeds
>   up _res object allocation/resolv_conf attachment).

With my recent pushes, I think we now have decent test coverages.
tst-resolv-threads tests various name resolution functions concurrently,
without patching the thread-local _res data structures, so it is
hopefully quite realistic.

I addressed the other issues as well.

I think we should postpone these changes:

> * Eliminate some locking in resolv/resolv_conf.c.
> * Reimplement the libresolv compat gethostname on top of NSS.

And perhaps not implement the first one at all (unless the lock shows up
in profiles).

Thanks,
Florian