[SSSD] [sssd PR#378][opened] [RFC] Use GNULIB's compiler warning code

[fidencio]

   URL: https://github.com/SSSD/sssd/pull/378
Author: fidencio
 Title: #378: [RFC] Use GNULIB's compiler warning code
Action: opened

PR body:
"""
This is the 3rd tentative to have this patch reviewed. For more references, please, see:
PR #50.

So, I've re-worked those patches a little bit and here is the time difference when
running reconfing with the patches:
```
real	0m26.047s
user	0m21.318s
sys	0m4.635s
```

And now without:
```
real	0m25.565s
user	0m20.696s
sys	0m4.433s
```

This patch set is rebased on top of PR #377.

I really would appreciate if someone could review and give their opinion.

The reason this PR was blocked is because this time difference has been considered a
"performance issue".

@jhrozek , could you take a look on this?
"""

To pull the PR as Git branch:
git remote add ghsssd https://github.com/SSSD/sssd
git fetch ghsssd pull/378/head:pr378
git checkout pr378