Add msgtypes.h include to pubsub_build.h

(The header won't compile without it.)

src/lib/pubsub/pubsub_build.h

@@ -14,6 +14,8 @@
 #ifndef TOR_PUBSUB_BUILD_H
 #define TOR_PUBSUB_BUILD_H
 
+#include "lib/dispatch/msgtypes.h"
+
 struct dispatch_t;
 
 /**