pipeline: add SWX Tx and emit instructions
pipeline: add SWX Tx and emit instructions

Add header emit and packet transmission instructions. Emit adds to the
output packet a header that is either generated (e.g. read from table
entry by action) or extracted from the input packet. Tx ends the
pipeline processing; discard is implemented by tx to special port.

Signed-off-by: Cristian Dumitrescu <25468b8a3698eeb3c368247f8635924bb4a1ce2c@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk