Makefile knows that a binary depends on .o file,
and the .o file depends on .c file, and adds the
per-target variables even in the indirect case.
Therefore, .o suffix is not needed here.

Note that it not hurts to leave it as is, so this commit
is done only for the sake of keeping things simple.
Signed-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>