librdmacm/rsocket: Succeed setsockopt REUSEADDR on connected sockets

librdmacm/rsocket: Succeed setsockopt REUSEADDR on connected sockets

The RDMA CM fail calls to set REUSEADDR on an rdma_cm_id if
it is not in the idle state.  As a result, this causes a failure
in NetPipe when run with socket calls intercepted by rsockets.
Fix this by returning success when REUSEADDR is set on an rsocket
that has already been connected.  When running over IB, REUSEADDR
is not necessary, since the TCP/IP addresses are mapped.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>