The way the Makefile is written, parasite.h is added
to gcc command line, like this:

  gcc -o spy spy.c libcompel.a parasite.h

Surely this is not what we want, as parasite.h is included to spy.c

The fix is to use "order-only prerequisite", as described by
https://www.gnu.org/software/make/manual/html_node/Prerequisite-Types.htmlSigned-off-by: Kir Kolyshkin <kir@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>