make: Fix dependency generation

In case if no goals specified the all
goal is implied so don't forget to generate
deps. This as well fixes a problem where
two "make clean" in a row forced build system
to regenerate deps.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Looks-good-to: Stanislav Kinsbursky <skinsbursky@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>