reorder ffmpeg to be lower priority than gme

This should prevent ffmpeg from taking priority over the gme plugin.
The ffmpeg plugin is more buggy than gme.
One of the prominent bugs of preferring ffmpeg over gme is that ffmpeg
cannot seek SAP files while gme can. This should prevent that from
happening.

NEWS

@@ -4,6 +4,7 @@ ver 0.23.13 (not yet released)
 * archive
   - zzip: fix crash bug
 * decoder
+  - ffmpeg: reorder to a lower priority than "gme"
   - gme: require GME 0.6 or later
 * output
   - pipewire: fix corruption bug due to missing lock

src/decoder/DecoderList.cxx

@@ -114,11 +114,11 @@ constexpr const struct DecoderPlugin *decoder_plugins[] = {
 #ifdef ENABLE_ADPLUG
 	&adplug_decoder_plugin,
 #endif
-#ifdef ENABLE_FFMPEG
-	&ffmpeg_decoder_plugin,
-#endif
 #ifdef ENABLE_GME
 	&gme_decoder_plugin,
+#endif
+#ifdef ENABLE_FFMPEG
+	&ffmpeg_decoder_plugin,
 #endif
 	&pcm_decoder_plugin,
 	nullptr