skiboot/libfdt/ is a minimally modified version of upstream libfdt that is
distributed with the dtc project hosted at github.com/dgibson/dtc.git.

This version is taken from dtc commit 243176c ("Fix bogus error on rebuild")

The modifications from upstream are the additions of this file, and
Makefile.inc which has been derived from Makefile.libfdt.

Local libfdt changes should be kept to a minimum, and submitted upstream if
possible.