pkgtools/plist-utils and red-black tree implementations

[Frédéric Fauberteau <triaxx%NetBSD.org@localhost>]

Hi,

I tried to build pkgtools/plist-utils on FreeBSD and I got:
plist_tree.c:37:10: fatal error: 'sys/rbtree.h' file not found
#include <sys/rbtree.h>
         ^~~~~~~~~~~~~~
1 error generated.
*** Error code 1

I found that OpenBSD (and FreeBSD too) provides sys/tree.h that contains 
a red-black tree implementation. Actually, NetBSD also provides 
sys/tree.h and then two red-black tree implementations.

Is there relevent differences between these implementations 
(sys/rbtree.h vs sys/tree.h)?

Could plist-utils use sys/tree.h in order to work on FreeBSD/OpenBSD?