doxygen: fix for doxygen 1.10.0 and later

doygen 1.10.0 changed the paths that include files are searched, with
the consequence for alsa-lib that the "Topics" tab is no longer fully
populated.

To fix this we need to prevent circular #include references when doygen
scans its input files, and also to re-order some macros.

include/seqmid.h

@@ -25,15 +25,15 @@
  *
  */
 
+#ifndef __ALSA_SEQMID_H
+#define __ALSA_SEQMID_H
+
 #if !defined(__ASOUNDLIB_H) && !defined(ALSA_LIBRARY_BUILD)
 /* don't use ALSA_LIBRARY_BUILD define in sources outside alsa-lib */
 #warning "use #include <alsa/asoundlib.h>, <alsa/seqmid.h> should not be used directly"
 #include <alsa/asoundlib.h>
 #endif
 
-#ifndef __ALSA_SEQMID_H
-#define __ALSA_SEQMID_H
-
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -48,7 +48,7 @@ extern "C" {
 /**
  * \brief initialize event record
  * \param ev event record pointer
- * 
+ *
  * This macro clears the given event record pointer to the default status.
  */
 static inline void snd_seq_ev_clear(snd_seq_event_t *ev)
@@ -130,7 +130,7 @@ static inline void snd_seq_ump_ev_clear(snd_seq_ump_event_t *ev)
  *
  * This macro sets the event to the direct passing mode
  * to be delivered immediately without queueing.
- * 
+ *
  * \sa snd_seq_ev_schedule_tick(), snd_seq_ev_schedule_real()
  */
 #define snd_seq_ev_set_direct(ev) \