Streamline and simplify IO Polling
Streamline and simplify IO Polling

Get more performance improvements by moving more of the
serialized effort into the IO thread to avoid churn.  This
also simplifies the issue with select being called without
recvfrom, allowing removal of the ignoresockets mechanism.
Also rework wait to avoid having to build lists that no one
ever consumes and move work out of the eternal loop
that only should happen at startup.  This has shaved an
additional 25% off of wallclock time in a single-processor
context for a given workload.

Change-Id: If321a69fabfb3ee55599ecfe3d24fbacd33388b5

stackforge/pyghmi,openstack/pyghmi,benoit-canet/pyghmi,openstack/pyghmi