Help IWYU understand headers.

Change-Id: Ieaa9e70d566b759d9c3664381bc5a6ab48c2575f
diff --git a/aos/configuration.h b/aos/configuration.h
index f1bcece..5579334 100644
--- a/aos/configuration.h
+++ b/aos/configuration.h
@@ -8,7 +8,7 @@
 
 #include <string_view>
 
-#include "aos/configuration_generated.h"
+#include "aos/configuration_generated.h"  // IWYU pragma: export
 #include "aos/flatbuffers.h"
 
 namespace aos {
diff --git a/aos/events/event_loop.h b/aos/events/event_loop.h
index 6ffb0fe..dc458e7 100644
--- a/aos/events/event_loop.h
+++ b/aos/events/event_loop.h
@@ -753,6 +753,6 @@
 
 }  // namespace aos
 
-#include "aos/events/event_loop_tmpl.h"
+#include "aos/events/event_loop_tmpl.h"  // IWYU pragma: export
 
 #endif  // AOS_EVENTS_EVENT_LOOP_H
diff --git a/aos/flatbuffers.h b/aos/flatbuffers.h
index 5da7466..39b072b 100644
--- a/aos/flatbuffers.h
+++ b/aos/flatbuffers.h
@@ -7,7 +7,7 @@
 #include "absl/types/span.h"
 #include "aos/containers/resizeable_buffer.h"
 #include "aos/macros.h"
-#include "flatbuffers/flatbuffers.h"
+#include "flatbuffers/flatbuffers.h"  // IWYU pragma: export
 #include "glog/logging.h"
 
 namespace aos {