net: define PACKET_TIMESTAMP

It's required for compiling on RHEL6
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

include/sk-packet.h

 #ifndef __CR_SK_PACKET_H__
 #define __CR_SK_PACKET_H__
+
+#ifndef PACKET_TIMESTAMP
+#define PACKET_TIMESTAMP	17
+#endif
+
 struct cr_fdset;
 struct fd_parms;
 struct cr_options;