Import libconfig am: 1199caa2e8 am: 604433215f am: 9effa07f5b am: 2426ed1f1a

Original change: https://android-review.googlesource.com/c/platform/external/libconfig/+/1772393

Change-Id: Ibd4ac853f0351e8b9273b185c0f3994dc66f3207