pcm: added pcm_convert_deinit(), pcm_resample_deinit()

Free memory allocated by libsamplerate when the output or the decoder
is closed.

src/decoder_thread.c

@@ -124,6 +124,8 @@ static void decoder_run_song(const struct song *song, const char *uri)
 		return;
 	}
 
+	pcm_convert_init(&decoder.conv_state);
+
 	ret = false;
 	if (!song_is_file(song)) {
 		unsigned int next = 0;
@@ -187,6 +189,8 @@ static void decoder_run_song(const struct song *song, const char *uri)
 		}
 	}
 
+	pcm_convert_deinit(&decoder.conv_state);
+
 	music_pipe_flush();
 
 	if (close_instream)