*: use gcc.h macros instead of GLib

src/mixer/AlsaMixerPlugin.cxx

@@ -73,6 +73,7 @@ public:
 /**
  * The quark used for GError.domain.
  */
+gcc_const
 static inline GQuark
 alsa_mixer_quark(void)
 {
@@ -124,7 +125,7 @@ AlsaMixerMonitor::DispatchSockets()
  */
 
 static int
-alsa_mixer_elem_callback(G_GNUC_UNUSED snd_mixer_elem_t *elem, unsigned mask)
+alsa_mixer_elem_callback(gcc_unused snd_mixer_elem_t *elem, unsigned mask)
 {
 	if (mask & SND_CTL_EVENT_MASK_VALUE)
 		GlobalEvents::Emit(GlobalEvents::MIXER);
@@ -149,8 +150,8 @@ AlsaMixer::Configure(const config_param &param)
 }
 
 static Mixer *
-alsa_mixer_init(G_GNUC_UNUSED void *ao, const config_param &param,
-		G_GNUC_UNUSED GError **error_r)
+alsa_mixer_init(gcc_unused void *ao, const config_param &param,
+		gcc_unused GError **error_r)
 {
 	AlsaMixer *am = new AlsaMixer();
 	am->Configure(param);
@@ -169,7 +170,7 @@ alsa_mixer_finish(Mixer *data)
 	snd_config_update_free_global();
 }
 
-G_GNUC_PURE
+gcc_pure
 static snd_mixer_elem_t *
 alsa_mixer_lookup_elem(snd_mixer_t *handle, const char *name, unsigned idx)
 {

src/mixer/OssMixerPlugin.cxx

@@ -104,7 +104,7 @@ OssMixer::Configure(const config_param &param, GError **error_r)
 }
 
 static Mixer *
-oss_mixer_init(G_GNUC_UNUSED void *ao, const config_param &param,
+oss_mixer_init(gcc_unused void *ao, const config_param &param,
 	       GError **error_r)
 {
 	OssMixer *om = new OssMixer();

src/mixer/PulseMixerPlugin.cxx

@@ -77,7 +77,7 @@ pulse_mixer_offline(PulseMixer *pm)
  * value.
  */
 static void
-pulse_mixer_volume_cb(G_GNUC_UNUSED pa_context *context, const pa_sink_input_info *i,
+pulse_mixer_volume_cb(gcc_unused pa_context *context, const pa_sink_input_info *i,
 		      int eol, void *userdata)
 {
 	PulseMixer *pm = (PulseMixer *)userdata;
@@ -120,7 +120,7 @@ pulse_mixer_update(PulseMixer *pm,
 }
 
 void
-pulse_mixer_on_connect(G_GNUC_UNUSED PulseMixer *pm,
+pulse_mixer_on_connect(gcc_unused PulseMixer *pm,
 		       struct pa_context *context)
 {
 	pa_operation *o;
@@ -182,7 +182,7 @@ pulse_mixer_finish(Mixer *data)
 }
 
 static int
-pulse_mixer_get_volume(Mixer *mixer, G_GNUC_UNUSED GError **error_r)
+pulse_mixer_get_volume(Mixer *mixer, gcc_unused GError **error_r)
 {
 	PulseMixer *pm = (PulseMixer *) mixer;
 	int ret;

src/mixer/WinmmMixerPlugin.cxx

@@ -61,7 +61,7 @@ winmm_volume_encode(int volume)
 
 static Mixer *
 winmm_mixer_init(void *ao, gcc_unused const config_param &param,
-		 G_GNUC_UNUSED GError **error_r)
+		 gcc_unused GError **error_r)
 {
 	assert(ao != nullptr);