In the port dir but all dependencies that are already installed will not show up anymore. It's a chain of if conditions that shows what would be done by make in the current situation. Something must differ if you add a FLAVOR= assignment to the make command that's recognized..But I don't know which directory to start `make -n` in.
It might not be exactly what you were hoping for.But there is no way to ask the ports tree for that info?
$ /usr/ports/Tools/scripts/portsearch qemu-guest-agent
Port: qemu-guest-agent-11.1.0
Path: /usr/ports/emulators/qemu
Info: QEMU CPU Emulator (guest agent)
Maint: bofh@FreeBSD.org
Index: emulators
B-deps: ...