mpxyd: add inline support, eager completion, improve proxy resource management

mpxyd: add inline support, eager completion, improve proxy resource management

Add inline support for MIX and IB dma channels

Add eager completion, configurable, to signal writes or sends
after scif_readfrom is signaled and all data is local to proxy
instead of waiting for IB signal. User data on MIC is available
for reuse.

Combine sends and writes to mix_post_send command, provide
ordering guarantees between inline and dma data. Allow's
direct posting from OP thread is head of queue.

Add new counters for inline and signaled IO.

Extend m_wr to include flags for controlling eager completions
and proxy buffer and work request management.

cq event FD is now non-blocking and processed via TX thread
instead of OP thread. Allows for polling > 1 event at a time.

Signed-off-by: Arlin Davis <arlin.r.davis@intel.com>