oss4: Address unused but set variables

GCC 4.6.x complains about such variable usage. Unused but set variables
were removed except that gst_oss4_mixer_slider_set_mute () now returns
the value from the call to gst_oss4_mixer_set_control_val ().

sys/oss4/oss4-mixer-slider.c

@@ -219,7 +219,7 @@ gst_oss4_mixer_slider_set_mute (GstOss4MixerSlider * s, gboolean mute)
     }
     ret = gst_oss4_mixer_set_control_val (s->mixer, s->mc, volume);
   } else {
-    ret = gst_oss4_mixer_set_control_val (s->mixer, s->mc->mute, !!mute);
+    ret = gst_oss4_mixer_set_control_val (s->mixer, s->mc->mute, ! !mute);
   }
 
   if (mute) {
@@ -228,7 +228,7 @@ gst_oss4_mixer_slider_set_mute (GstOss4MixerSlider * s, gboolean mute)
     track->flags &= ~GST_MIXER_TRACK_MUTE;
   }
 
-  return FALSE;
+  return ret;
 }
 
 GstMixerTrack *
@@ -286,7 +286,7 @@ gst_oss4_mixer_slider_process_change_unlocked (GstMixerTrack * track)
 
   if (s->mc->mute != NULL && s->mc->mute->changed) {
     gst_mixer_mute_toggled (GST_MIXER (s->mixer), track,
-        !!s->mc->mute->last_val);
+        ! !s->mc->mute->last_val);
   } else {
     /* nothing to do here, since we don't/can't easily implement the record
      * flag */

sys/oss4/oss4-mixer-switch.c

@@ -84,7 +84,6 @@ gboolean
 gst_oss4_mixer_switch_get (GstOss4MixerSwitch * s, gboolean * disabled)
 {
   GstMixerTrack *track;
-  int flag;
   int enabled = -1;
 
   track = GST_MIXER_TRACK (s);
@@ -95,8 +94,6 @@ gst_oss4_mixer_switch_get (GstOss4MixerSwitch * s, gboolean * disabled)
     return FALSE;
   }
 
-  flag = (enabled == 0) ? GST_MIXER_TRACK_MUTE : 0;
-
   if (enabled) {
     track->flags &= ~GST_MIXER_TRACK_MUTE;
   } else {

sys/oss4/oss4-property-probe.c

@@ -283,7 +283,6 @@ gst_oss4_property_probe_get_values (GstPropertyProbe * probe,
     guint prop_id, const GParamSpec * pspec)
 {
   struct oss_sysinfo si = { {0,}, };
-  GstElementClass *klass;
   GValueArray *array = NULL;
   GstObject *obj;
   GList *devices, *l;
@@ -299,7 +298,6 @@ gst_oss4_property_probe_get_values (GstPropertyProbe * probe,
   GST_OBJECT_LOCK (obj);
 
   /* figure out whether the element is a source or sink */
-  klass = GST_ELEMENT_GET_CLASS (GST_ELEMENT (probe));
   if (GST_IS_OSS4_SINK (probe)) {
     GST_DEBUG_OBJECT (probe, "probing available output devices");
     cap_mask = PCM_CAP_OUTPUT;

sys/oss4/oss4-source.c

@@ -121,15 +121,11 @@ static void
 gst_oss4_source_class_init (GstOss4SourceClass * klass)
 {
   GObjectClass *gobject_class;
-  GstElementClass *gstelement_class;
   GstBaseSrcClass *gstbasesrc_class;
-  GstBaseAudioSrcClass *gstbaseaudiosrc_class;
   GstAudioSrcClass *gstaudiosrc_class;
 
   gobject_class = (GObjectClass *) klass;
-  gstelement_class = (GstElementClass *) klass;
   gstbasesrc_class = (GstBaseSrcClass *) klass;
-  gstbaseaudiosrc_class = (GstBaseAudioSrcClass *) klass;
   gstaudiosrc_class = (GstAudioSrcClass *) klass;
 
   gobject_class->dispose = gst_oss4_source_dispose;
@@ -928,16 +924,12 @@ static void
 gst_oss4_source_mixer_set_mute (GstMixer * mixer, GstMixerTrack * track,
     gboolean mute)
 {
-  GstOss4Source *oss;
-
   g_return_if_fail (mixer != NULL);
   g_return_if_fail (track != NULL);
   g_return_if_fail (GST_IS_MIXER_TRACK (track));
   g_return_if_fail (GST_IS_OSS4_SOURCE (mixer));
   g_return_if_fail (GST_OSS4_SOURCE_IS_OPEN (mixer));
 
-  oss = GST_OSS4_SOURCE (mixer);
-
   /* FIXME: implement gst_oss4_source_mixer_set_mute() - what to do here? */
   /* oss4_mixer_set_mute (mixer->mixer, track, mute); */
 }