message: demo: Even more indexcodec coverage
  To trip the end-of-data mid-decode, we need more than one triangle that
  uses data section of the buffer...
diff: @@ -536,9 +536,12 @@ void encodeIndex(const Mesh& mesh)
  void encodeIndexCoverage()
  {
  - const unsigned int indices[] = { 0, 1, 2, 2, 1, 3, 4, 6, 5 };
  + // note: 4 6 5 triangle here is a combo-breaker:
  + // we encode it without rotating, a=next, c=next - this means we do *not* bump next to 6
  + // which means that the next triangle can't be encoded via next sequencing!
  + const unsigned int indices[] = { 0, 1, 2, 2, 1, 3, 4, 6, 5, 7, 8, 9 };
  const size_t index_count = sizeof(indices) / sizeof(indices[0]);
  - const size_t vertex_count = 7;
  + const size_t vertex_count = 10;
  std::vector<unsigned char> buffer(meshopt_encodeIndexBufferBound(index_count, vertex_count));
  buffer.resize(meshopt_encodeIndexBuffer(&buffer[0], buffer.size(), indices, index_count));
  