[sssd PR#5223][comment] [wip] Add .clang-format

[pbrezina]

URL: https://github.com/SSSD/sssd/pull/5223
Title: #5223: [wip] Add .clang-format

pbrezina commented:
"""
I pushed little update. So far it works great for development. But it has some issues when trying to automatically correct the coding style in some scenarios. It tries to change more code then it is supposed to when git diff creates bigger snippet then a small change self-contained change.
"""

See the full comment at https://github.com/SSSD/sssd/pull/5223#issuecomment-660077063