Discovered while trying to cross-build `make ftp` on macOS, it seems that we should not use the host's install(1) to make ftp tarballs, but use the freshly built one.
install(1) on macOS is much older than the FreeBSD version and missing some options. It does not work at all. On FreeBSD the host /usr/bin/install will usually work - except after a new required option was added.
This patch solves the problem on macOS.