pkt-gen: Bug fix on pinger-body.

This patch fixes a bug that pinger-body embeds 16-byte
struct timespec into a 14 byte payload space (after 4 byte
sequence number)
pkt-gen: Fix a problem that the multi-threaded
receiver_body() does not terminate with ctl+c
before the first receive
[pkt-gen] Fixed the init of number of queues

If pkt-gen is in trasmission, get the number of tx queues, otherwise
if it is received, get the number of rx queues.
linux/scripts: always make the cache dir
linux/scripts: make check-patch work with 99999
linux: Implement netmap_{re,un}load_map
netmap_mem2: DMA mapping in deref/finalize
linux/ixgbe: add pci_device in netmap_attach
linux/e1000: add pci_device in netmap_attach
linux/igb: add pci_device in netmap_attach
linux/realtek: add pci_device in netmap_attach
linux/forcedeth: add pci_device in netmap_attach
linux/mlx4: add pci_device in netmap_attach
linux/iommu: add nm_grp to differ allocators

* Initial support towards a per iommu group global allocators
for NICs
netmap: add pci_device in netmap_bwrap_attach

* `pdev` needs to be set in netmap_adapter for the NIC/vport
to be make the buffers visible for the device.
merge NAF_NATIVE_ON / NAF_NETMAP_ON helpers
linux: use iommu only in linux >= 3.6
fix need_rxkick in paravirt mode
better check for virtual header size
fix build of iommu support under FreeBSD

code is not supported but some arguments have the wrong types when used
on FreeBSD)