SDP: various bzcopy fixes V2

SDP: various bzcopy fixes V2

The Mellanox regression tests posted a number of failures when
multiple threads were accessing the same sockets concurrently.  In
addition to test failures, there were log messages of the form:
  sdp_sock(54386:19002): Could not reap -5 in-flight sends

This fix handles all these failures and errors.

The V2 is a fix to handle 2.6.22+ kernels where sk_buffs have
changed.

Signed-off-by: Jim Mott <jim@mellanox.com>