decoder_plugin: pass struct config_param to init() method

Preparing for per-plugin configuration sections in mpd.conf.

src/decoder/ffmpeg_plugin.c

@@ -120,7 +120,8 @@ static URLProtocol mpd_ffmpeg_fileops = {
 	.url_close = mpd_ffmpeg_close,
 };
 
-static bool ffmpeg_init(void)
+static bool
+ffmpeg_init(G_GNUC_UNUSED const struct config_param *param)
 {
 	av_register_all();
 	register_protocol(&mpd_ffmpeg_fileops);

src/decoder/flac_plugin.c

@@ -383,7 +383,7 @@ flac_decode(struct decoder * decoder, struct input_stream *input_stream)
 #ifndef HAVE_OGGFLAC
 
 static bool
-oggflac_init(void)
+oggflac_init(G_GNUC_UNUSED const struct config_param *param)
 {
 #if defined(FLAC_API_VERSION_CURRENT) && FLAC_API_VERSION_CURRENT > 7
 	return !!FLAC_API_SUPPORTS_OGG_FLAC;

src/decoder/fluidsynth_plugin.c

@@ -64,7 +64,7 @@ fluidsynth_mpd_log_function(int level, char *message, G_GNUC_UNUSED void *data)
 }
 
 static bool
-fluidsynth_init(void)
+fluidsynth_init(G_GNUC_UNUSED const struct config_param *param)
 {
 	fluid_set_log_function(LAST_LOG_LEVEL,
 			       fluidsynth_mpd_log_function, NULL);

src/decoder/mikmod_plugin.c

@@ -90,7 +90,8 @@ static MDRIVER drv_mpd = {
 	VC_VoiceRealVolume
 };
 
-static bool mod_initMikMod(void)
+static bool
+mod_initMikMod(G_GNUC_UNUSED const struct config_param *param)
 {
 	static char params[] = "";
 

src/decoder/mp3_plugin.c

@@ -91,7 +91,8 @@ mad_fixed_to_24_buffer(int32_t *dest, const struct mad_synth *synth,
 	}
 }
 
-static bool mp3_plugin_init(void)
+static bool
+mp3_plugin_init(G_GNUC_UNUSED const struct config_param *param)
 {
 	gapless_playback = config_get_bool(CONF_GAPLESS_MP3_PLAYBACK,
 					   DEFAULT_GAPLESS_MP3_PLAYBACK);

src/decoder/wildmidi_plugin.c

@@ -30,7 +30,7 @@ enum {
 };
 
 static bool
-wildmidi_init(void)
+wildmidi_init(G_GNUC_UNUSED const struct config_param *param)
 {
 	int ret;