if a port sets FAKE=Yes, this means it can be `pre'-installed elsewhere,
with DESTDIR set to WRKINST (=work/fake-${ARCH} by default).
the infrastructure takes care of pre-install/do-install/post-install targets,
assuming those install stuff under PREFIX.
To help ports to cope with DESTDIR, you can set FAKE_FLAGS and FAKE_TARGET
(used for the fake installation).
Ports with FAKE=Yes are the way to go: they can be packaged directly without
a real installation, and the installation proceeds from the package, thus
forcing porters to check the package.