Return 0(success) in EventBaseEvent::eb_event_base_set if we're trying to use...

Return 0(success) in EventBaseEvent::eb_event_base_set if we're trying to use a non libevent backend

Summary: Return 0(success) in EventBaseEvent::eb_event_base_set if we're trying to use a non libevent backend

Reviewed By: kevin-vigor

Differential Revision: D20513609

fbshipit-source-id: 8329c614f728a86d1bd5267652c39c8d4f54f6cd

folly/io/async/EventBaseBackendBase.cpp

@@ -30,7 +30,7 @@ int EventBaseEvent::eb_event_base_set(EventBase* evb) {
     return ::event_base_set(base, &event_);
   }
 
-  return -1;
+  return 0;
 }
 
 int EventBaseEvent::eb_event_add(const struct timeval* timeout) {