Try the JACK backend before PulseAudio

The backend will not spawn a server by default, so PulseAudio will still be
preferred as long as a JACK server isn't already running.

Alc/ALc.c

@@ -61,6 +61,9 @@ struct BackendInfo {
 
 #define EmptyFuncs { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL }
 static struct BackendInfo BackendList[] = {
+#ifdef HAVE_JACK
+    { "jack", ALCjackBackendFactory_getFactory, NULL, NULL, NULL, EmptyFuncs },
+#endif
 #ifdef HAVE_PULSEAUDIO
     { "pulse", ALCpulseBackendFactory_getFactory, NULL, NULL, NULL, EmptyFuncs },
 #endif
@@ -82,9 +85,6 @@ static struct BackendInfo BackendList[] = {
 #ifdef HAVE_QSA
     { "qsa", NULL, alc_qsa_init, alc_qsa_deinit, alc_qsa_probe, EmptyFuncs },
 #endif
-#ifdef HAVE_JACK
-    { "jack", ALCjackBackendFactory_getFactory, NULL, NULL, NULL, EmptyFuncs },
-#endif
 #ifdef HAVE_MMDEVAPI
     { "mmdevapi", ALCmmdevBackendFactory_getFactory, NULL, NULL, NULL, EmptyFuncs },
 #endif