[SSSD] [sssd PR#458][comment] overrides: fixes for sysdb_invalidate_overrides()

[sumit-bose]

URL: https://github.com/SSSD/sssd/pull/458
Title: #458: overrides: fixes for sysdb_invalidate_overrides()

sumit-bose commented:
"""
Thank you for the review, the latest version includes both of your comments.
"""

See the full comment at https://github.com/SSSD/sssd/pull/458#issuecomment-348518269