https://bugs.gentoo.org/918421
https://github.com/MusicPlayerDaemon/MPD/issues/1898
--- a/src/decoder/plugins/FfmpegIo.cxx
+++ b/src/decoder/plugins/FfmpegIo.cxx
@@ -26,6 +26,9 @@

 extern "C" {
 #include <libavutil/mem.h>
+#if LIBAVUTIL_VERSION_INT >= AV_VERSION_INT(58, 29, 100)
+#include <libavutil/error.h>
+#endif
 }

 AvioStream::~AvioStream()