Makefiles: don't use the FORCE, Luke!

With GNU make, using .PHONY leads to the same result as using
the "FORCE" hack, but unlike FORCE is not a hack. Since we do not
plan to use any other make than GNU make, let's just mark phony
targets as such.

For more details about why PHONY is better than FORCE, see
http://www.gnu.org/software/make/manual/make.html#index-FORCE



[v2: rebased and splitted]

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>