The rte_ring used for pollers is already single-producer and
single-consumer, so it is not providing any thread safety guarantees.
ALl modifications to the active_pollers ring are done from the core that
is running the reactor (via events). This means the rte_ring can be
replaced with a simpler intrusive linked list.
This simplifies the removal of pollers in the middle of the list and
avoids extra allocations for the ring.
Change-Id: Ica149b7a1668a8af1e6ca8f741c48f2217f6f9bf
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>