compilation fix on old kernels
compilation fix on old kernels

ntop/PF_RING,opencTM/PF_RING,ntop/PF_RING,opencTM/PF_RING,ntop/PF_RING,opencTM/PF_RING,ntop/PF_RING,ntop/PF_RING,opencTM/PF_RING,ntop/PF_RING,ntop/PF_RING