decoder: make all decoder_plugin structs const

All decoder_plugin structs are initialized at compile time, and must
never change.

src/decoder/aac_plugin.c

@@ -589,7 +589,7 @@ static struct tag *aacTagDup(const char *file)
 static const char *aac_suffixes[] = { "aac", NULL };
 static const char *aac_mimeTypes[] = { "audio/aac", "audio/aacp", NULL };
 
-struct decoder_plugin aacPlugin = {
+const struct decoder_plugin aacPlugin = {
 	.name = "aac",
 	.stream_decode = aac_stream_decode,
 	.file_decode = aac_decode,

src/decoder/audiofile_plugin.c

@@ -135,7 +135,7 @@ static struct tag *audiofileTagDup(const char *file)
 
 static const char *audiofileSuffixes[] = { "wav", "au", "aiff", "aif", NULL };
 
-struct decoder_plugin audiofilePlugin = {
+const struct decoder_plugin audiofilePlugin = {
 	.name = "audiofile",
 	.file_decode = audiofile_decode,
 	.tag_dup = audiofileTagDup,

src/decoder/ffmpeg_plugin.c

@@ -380,7 +380,7 @@ static const char *ffmpeg_Mimetypes[] = {
 	NULL
 };
 
-struct decoder_plugin ffmpegPlugin = {
+const struct decoder_plugin ffmpegPlugin = {
 	.name = "ffmpeg",
 	.init = ffmpeg_init,
 	.try_decode = ffmpeg_try_decode,

src/decoder/flac_plugin.c

@@ -435,7 +435,7 @@ static const char *oggflac_mime_types[] = { "audio/x-flac+ogg",
 					    "application/x-ogg",
 					    NULL };
 
-struct decoder_plugin oggflacPlugin = {
+const struct decoder_plugin oggflacPlugin = {
 	.name = "oggflac",
 	.try_decode = oggflac_try_decode,
 	.stream_decode = oggflac_decode,
@@ -452,7 +452,7 @@ static const char *flac_mime_types[] = { "audio/x-flac",
 					 "application/x-flac",
 					 NULL };
 
-struct decoder_plugin flacPlugin = {
+const struct decoder_plugin flacPlugin = {
 	.name = "flac",
 	.stream_decode = flac_decode,
 	.tag_dup = flacTagDup,

src/decoder/mod_plugin.c

@@ -281,7 +281,7 @@ static const char *modSuffixes[] = { "amf",
 	NULL
 };
 
-struct decoder_plugin modPlugin = {
+const struct decoder_plugin modPlugin = {
 	.name = "mod",
 	.finish = mod_finishMikMod,
 	.file_decode = mod_decode,

src/decoder/mp3_plugin.c

@@ -1146,7 +1146,7 @@ static struct tag *mp3_tag_dup(const char *file)
 static const char *mp3_suffixes[] = { "mp3", "mp2", NULL };
 static const char *mp3_mime_types[] = { "audio/mpeg", NULL };
 
-struct decoder_plugin mp3Plugin = {
+const struct decoder_plugin mp3Plugin = {
 	.name = "mp3",
 	.init = mp3_plugin_init,
 	.stream_decode = mp3_decode,

src/decoder/mp4_plugin.c

@@ -413,7 +413,7 @@ static struct tag *mp4TagDup(const char *file)
 static const char *mp4_suffixes[] = { "m4a", "mp4", NULL };
 static const char *mp4_mimeTypes[] = { "audio/mp4", "audio/m4a", NULL };
 
-struct decoder_plugin mp4Plugin = {
+const struct decoder_plugin mp4Plugin = {
 	.name = "mp4",
 	.stream_decode = mp4_decode,
 	.tag_dup = mp4TagDup,

src/decoder/mpc_plugin.c

@@ -297,7 +297,7 @@ static struct tag *mpcTagDup(const char *file)
 
 static const char *mpcSuffixes[] = { "mpc", NULL };
 
-struct decoder_plugin mpcPlugin = {
+const struct decoder_plugin mpcPlugin = {
 	.name = "mpc",
 	.stream_decode = mpc_decode,
 	.tag_dup = mpcTagDup,

src/decoder/oggflac_plugin.c

@@ -343,7 +343,7 @@ static const char *oggflac_mime_types[] = { "audio/x-flac+ogg",
 					    "application/x-ogg",
 					    NULL };
 
-struct decoder_plugin oggflacPlugin = {
+const struct decoder_plugin oggflacPlugin = {
 	.name = "oggflac",
 	.try_decode = oggflac_try_decode,
 	.stream_decode = oggflac_decode,

src/decoder/oggvorbis_plugin.c

@@ -374,7 +374,7 @@ static const char *oggvorbis_MimeTypes[] = { "application/ogg",
 					     "application/x-ogg",
 					     NULL };
 
-struct decoder_plugin oggvorbisPlugin = {
+const struct decoder_plugin oggvorbisPlugin = {
 	.name = "oggvorbis",
 	.try_decode = oggvorbis_try_decode,
 	.stream_decode = oggvorbis_decode,

src/decoder/wavpack_plugin.c

@@ -562,7 +562,7 @@ wavpack_filedecode(struct decoder *decoder, const char *fname)
 static char const *wavpackSuffixes[] = { "wv", NULL };
 static char const *wavpackMimeTypes[] = { "audio/x-wavpack", NULL };
 
-struct decoder_plugin wavpackPlugin = {
+const struct decoder_plugin wavpackPlugin = {
 	.name = "wavpack",
 	.try_decode = wavpack_trydecode,
 	.stream_decode = wavpack_streamdecode,

src/decoder_list.c

@@ -21,17 +21,17 @@
 
 #include <glib.h>
 
-extern struct decoder_plugin mp3Plugin;
-extern struct decoder_plugin oggvorbisPlugin;
-extern struct decoder_plugin flacPlugin;
-extern struct decoder_plugin oggflacPlugin;
-extern struct decoder_plugin audiofilePlugin;
-extern struct decoder_plugin mp4Plugin;
-extern struct decoder_plugin aacPlugin;
-extern struct decoder_plugin mpcPlugin;
-extern struct decoder_plugin wavpackPlugin;
-extern struct decoder_plugin modPlugin;
-extern struct decoder_plugin ffmpegPlugin;
+extern const struct decoder_plugin mp3Plugin;
+extern const struct decoder_plugin oggvorbisPlugin;
+extern const struct decoder_plugin flacPlugin;
+extern const struct decoder_plugin oggflacPlugin;
+extern const struct decoder_plugin audiofilePlugin;
+extern const struct decoder_plugin mp4Plugin;
+extern const struct decoder_plugin aacPlugin;
+extern const struct decoder_plugin mpcPlugin;
+extern const struct decoder_plugin wavpackPlugin;
+extern const struct decoder_plugin modPlugin;
+extern const struct decoder_plugin ffmpegPlugin;
 
 static const struct decoder_plugin *const decoder_plugins[] = {
 #ifdef HAVE_MAD