include/vzsyscalls.h: only define __NR_ioprio_set if undef

Recent distros come with includes that have __NR_ioprio_set
already defined, so let's only define it if it is missing.

Helps to avoid this warning:

	warning: "__NR_ioprio_set" redefined

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed