l4p/tcp_ofo: fix handling out-of-order packets

l4p/tcp_ofo: fix handling out-of-order packets

Problems are:
  1. ofodb could not be assigned directly, as direct assignment does not
     copy the mbuf pointer area belonging to it.

  2. _ofo_insert_new and _ofo_insert_right doesn't remove overlap correctly.

  3. _ofo_insert_new insert new db in wrong position.

  4. rx_ofo_reduce sets wrong seq, and would insert overlapped data into
     rx queue.

  5. _ofo_compact may miss compacting some ofodbs and doesn't update partly
     moved ofodb correctly.

Change-Id: I03f1065ef5a15ef2abc664f9cc98910aab72d39b
Signed-off-by: Jielong Zhou <jielong.zjl@antfin.com>