New review comment by agausmann on void-packages repository

https://github.com/void-linux/void-packages/pull/38253#discussion_r928321216

Comment:
I've tried a gnu-makefile build style just like you suggested (also making sure move the `vlicense LICENSE` to `post_install`), but I get this error:
```
opensmtpd.c:19:10: fatal error: sys/tree.h: No such file or directory
   19 | #include <sys/tree.h>
      |          ^~~~~~~~~~~~
compilation terminated.
```
Adding `libbsd-devel` to makedepends doesn't seem to fix it either.