Resolve Solaris build issues and add some API documentation.

(issue #14981)
Reported by: snuffy


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@190989 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/asterisk/channel.h

@@ -2073,8 +2073,27 @@ struct ast_group_info {
 		} \
 	} while (0)
 
+/*!
+ * \brief Increase channel reference count
+ *
+ * \param c the channel
+ *
+ * \retval c always
+ *
+ * \since 1.6.3
+ */
 #define ast_channel_ref(c) ({ ao2_ref(c, +1); (c); })
-#define ast_channel_unref(c) ({ ao2_ref(c, -1); (NULL); })
+
+/*!
+ * \brief Decrease channel reference count
+ *
+ * \param c the channel
+ *
+ * \retval NULL always
+ *
+ * \since 1.6.3
+ */
+#define ast_channel_unref(c) ({ ao2_ref(c, -1); (struct ast_channel *) (NULL); })
 
 /*! Channel Iterating @{ */
 

main/rtp_engine.c

@@ -1540,7 +1540,8 @@ int ast_rtp_instance_make_compatible(struct ast_channel *chan, struct ast_rtp_in
 
 	if (!peer_instance || peer_instance->engine != instance->engine) {
 		ast_channel_unlock(peer);
-		peer_instance = (ao2_ref(peer_instance, -1), NULL);
+		ao2_ref(peer_instance, -1);
+		peer_instance = NULL;
 		return -1;
 	}
 
@@ -1548,7 +1549,8 @@ int ast_rtp_instance_make_compatible(struct ast_channel *chan, struct ast_rtp_in
 
 	ast_channel_unlock(peer);
 
-	peer_instance = (ao2_ref(peer_instance, -1), NULL);
+	ao2_ref(peer_instance, -1);
+	peer_instance = NULL;
 
 	return res;
 }