Original commit message from CVS: * ext/alsa/gstalsamixer.c: (gst_alsa_mixer_open), (gst_alsa_mixer_close), (gst_alsa_mixer_supported), (gst_alsa_mixer_build_list), (gst_alsa_mixer_free_list), (gst_alsa_mixer_change_state), (gst_alsa_mixer_list_tracks), (gst_alsa_mixer_get_volume), (gst_alsa_mixer_set_volume), (gst_alsa_mixer_set_mute), (gst_alsa_mixer_set_record): Fix for cases where we fail to attach to a mixer.