gcc-6 is more strict WRT narrowing:
error: narrowing conversion of ‘-1’ from ‘int’ to ‘unsigned int’ inside { } [-Wnarrowing]

https://bugs.gentoo.org/594912
--- a/audio/hufftable.cpp
+++ b/audio/hufftable.cpp
@@ -552,3 +552,3 @@ const HUFFMANCODETABLE MPEGaudio::ht[HTN]=
 {
-  { 0, 0-1, 0-1, 0,  0, htd33},
+  { 0, ~0u, ~0u, 0,  0, htd33},
   { 1, 2-1, 2-1, 0,  7,htd01},
@@ -556,3 +556,3 @@ const HUFFMANCODETABLE MPEGaudio::ht[HTN]=
   { 3, 3-1, 3-1, 0, 17,htd03},
-  { 4, 0-1, 0-1, 0,  0, htd33},
+  { 4, ~0u, ~0u, 0,  0, htd33},
   { 5, 4-1, 4-1, 0, 31,htd05},
@@ -566,3 +566,3 @@ const HUFFMANCODETABLE MPEGaudio::ht[HTN]=
   {13,16-1,16-1, 0,511,htd13},
-  {14, 0-1, 0-1, 0,  0, htd33},
+  {14,~0u,  ~0u, 0,  0, htd33},
   {15,16-1,16-1, 0,511,htd15},