doxygen: add @file declarations for src/core/mainloop

If a file doesn't use the file command (either \file or @file),
Doxygen won't try to process it.

src/core/mainloop/mainloop_pubsub.c

@@ -4,6 +4,15 @@
  * Copyright (c) 2007-2018, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file mainloop_pubsub.c
+ * @brief Connect the publish-subscribe code to the main-loop.
+ *
+ * This module is responsible for instantiating all the channels used by the
+ * publish-subscribe code, and making sure that each one's messages are
+ * processed when appropriate.
+ **/
+
 #include "orconfig.h"
 
 #include "core/or/or.h"

src/core/mainloop/mainloop_pubsub.h

@@ -4,6 +4,11 @@
  * Copyright (c) 2007-2018, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file mainloop_pubsub.h
+ * @brief Header for mainloop_pubsub.c
+ **/
+
 #ifndef TOR_MAINLOOP_PUBSUB_H
 #define TOR_MAINLOOP_PUBSUB_H
 

src/core/mainloop/mainloop_sys.c

@@ -4,6 +4,11 @@
  * Copyright (c) 2007-2019, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file mainloop_sys.c
+ * @brief Declare the "mainloop" subsystem.
+ **/
+
 #include "core/or/or.h"
 #include "core/mainloop/mainloop_sys.h"
 #include "core/mainloop/mainloop.h"

src/core/mainloop/mainloop_sys.h

@@ -4,6 +4,11 @@
  * Copyright (c) 2007-2019, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file mainloop_sys.h
+ * @brief Header for mainloop_sys.c
+ **/
+
 #ifndef MAINLOOP_SYS_H
 #define MAINLOOP_SYS_H
 

src/core/mainloop/netstatus.c

@@ -4,6 +4,11 @@
  * Copyright (c) 2007-2019, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file netstatus.c
+ * @brief Track whether the network is disabled, dormant, etc.
+ **/
+
 #include "core/or/or.h"
 #include "core/mainloop/netstatus.h"
 #include "core/mainloop/mainloop.h"

src/core/mainloop/netstatus.h

@@ -4,6 +4,11 @@
  * Copyright (c) 2007-2019, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file netstatus.h
+ * @brief Header for netstatus.c
+ **/
+
 #ifndef TOR_NETSTATUS_H
 #define TOR_NETSTATUS_H
 

src/core/mainloop/periodic.h

 /* Copyright (c) 2015-2019, The Tor Project, Inc. */
 /* See LICENSE for licensing information */
 
+/**
+ * @file periodic.h
+ * @brief Header for periodic.c
+ **/
+
 #ifndef TOR_PERIODIC_H
 #define TOR_PERIODIC_H