jackaudio: use ifdefs to hide unavailable functions

On Windows the jack_set_thread_creator() function and on MacOS the
pthread_setname_np() function with a thread pointer paramater is
not available. Use #ifdefs to remove the jack_set_thread_creator()
function call and the qjack_thread_creator() function in both
cases.

The qjack_thread_creator() function just sets the name of the
created thread for debugging purposes and isn't really necessary.

From the jack_set_thread_creator() documentation:
(...)

No normal application/client should consider calling this. (...)

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/785


Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Message-Id: <20211226154017.6067-1-vr_qemu@t-online.de>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

audio/jackaudio.c

@@ -622,6 +622,7 @@ static void qjack_enable_in(HWVoiceIn *hw, bool enable)
     ji->c.enabled = enable;
 }
 
+#if !defined(WIN32) && defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
 static int qjack_thread_creator(jack_native_thread_t *thread,
     const pthread_attr_t *attr, void *(*function)(void *), void *arg)
 {
@@ -635,6 +636,7 @@ static int qjack_thread_creator(jack_native_thread_t *thread,
 
     return ret;
 }
+#endif
 
 static void *qjack_init(Audiodev *dev)
 {
@@ -687,7 +689,9 @@ static void register_audio_jack(void)
 {
     qemu_mutex_init(&qjack_shutdown_lock);
     audio_driver_register(&jack_driver);
+#if !defined(WIN32) && defined(CONFIG_PTHREAD_SETNAME_NP_W_TID)
     jack_set_thread_creator(qjack_thread_creator);
+#endif
     jack_set_error_function(qjack_error);
     jack_set_info_function(qjack_info);
 }