message: vertexcodec: Fix gcc-5 warning
  This breaks Travis ARM build
diff: @@ -914,6 +914,7 @@ int meshopt_decodeVertexBuffer(void* destination, size_t vertex_count, size_t ve
  #if defined(SIMD_SSE) || defined(SIMD_NEON)
  assert(gDecodeBytesGroupInitialized);
  + (void)gDecodeBytesGroupInitialized;
  #endif
  unsigned char* vertex_data = static_cast<unsigned char*>(destination);
  