Return the size of event that the Libevent library was compiled
with.
This will be NO GREATER than sizeof(struct event) if you're running with
the same version of Libevent that your application was built with, but
otherwise might not.
Note that it might be SMALLER than sizeof(struct event) if some future
version of Libevent adds extra padding to the end of struct event.
We might do this to help ensure ABI-compatibility between different
versions of Libevent.
Return the size of event that the Libevent library was compiled with.
This will be NO GREATER than sizeof(struct event) if you're running with the same version of Libevent that your application was built with, but otherwise might not.
Note that it might be SMALLER than sizeof(struct event) if some future version of Libevent adds extra padding to the end of struct event. We might do this to help ensure ABI-compatibility between different versions of Libevent.