I didn't look at this closely ...

gcc -I. -I. -I/usr/include/libnbcompat  -O2 -I/usr/include -Wl,-R/usr/lib
-L/usr/lib -o mtree compare.o crc.o create.o excludes.o mtree.o verify.o
-lnbcompat
excludes.o: In function `check_excludes':
excludes.o(.text+0xe5): undefined reference to `LIST_FIRST'
excludes.o(.text+0x12b): undefined reference to `LIST_NEXT'
collect2: ld returned 1 exit status
*** Error code 1

The wrapper log has:

/usr/bin/gcc -I. -I.
-I/tmp/pkgsrc/pkgtools/mtree/work.shasta/.buildlink/include/libnbcompat
-O2 -I/tmp/pkgsrc/pkgtools/mtree/work.shasta/.buildlink/include
-Wl,-R/usr/lib -L/tmp/pkgsrc/pkgtools/mtree/work.shasta/.buildlink/lib -o
mtree compare.o crc.o create.o excludes.o mtree.o verify.o -lnbcompat

I do have a /usr/include/sys/queue.h file, but it doesn't seem to define
these. (I also have  /usr/include/libnbcompat/nbcompat.h and
/usr/include/libnbcompat/util.h.)

   Jeremy C. Reed
   http://bsd.reedmedia.net/