Move event.h into ipc_lib

Makes tab completion a lot less annoying.

Change-Id: I0c905ba112c274d23b5f0277b9a5c2a8e4e238f6
diff --git a/aos/ipc_lib/queue_racer.cc b/aos/ipc_lib/queue_racer.cc
index fcc8668..5b3d88b 100644
--- a/aos/ipc_lib/queue_racer.cc
+++ b/aos/ipc_lib/queue_racer.cc
@@ -2,9 +2,10 @@
 
 #include <inttypes.h>
 #include <string.h>
+
 #include <limits>
 
-#include "aos/event.h"
+#include "aos/ipc_lib/event.h"
 #include "gtest/gtest.h"
 
 namespace aos {