evutil.h) will continue to work by including the corresponding new
headers. Old code should not be broken by this change.
-2.2. New thread-safe, binary-compatibile, harder-to-mess-up APIs
+2.2. New thread-safe, binary-compatible, harder-to-mess-up APIs
Some aspects of the historical Libevent API have encouraged
non-threadsafe code, or forced code built against one version of Libevent