Fix hosttar generation not to depend on PHONY targets

Instead of depending on the phony targets, which are never considered
clean (so the tar will always rebuild), and include all versions of a
particular module (host, target, etc), use the real files that we're
about to package.

Test: m hosttar
Test: cvd-host_package.tar.gz is the same before&after (except timestamps)
Change-Id: If5e28bfa33bc53e6d451ebd084ab69c2ba567034
1 file changed