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 ().
Code cleanups, general improvements, support for the
new mixer flags in latest gst-plugins-base.
Fixes: #584252
Patch By: Brian Cameron <brian.cameron@sun.com>
Patch By: Garrett D'Amore <garrett.damore@sun.com>