message: vertexcodec: Minor decodeVertexBlock refactoring
  Move vertex_count_aligned into a variable similarly to SIMD decoder.
  clang static analyzer trips up on buffer[i] access in this function,
  thinking that buffer might contain uninitialized element in
  0..vertex_count-1 range; I was hoping that adding an assertion that
  vertex_count <= vertex_count_alignment would work around that but it
  doesn't :(
diff: @@ -305,9 +305,11 @@ static const unsigned char* decodeVertexBlock(const unsigned char* data, const u
  unsigned char buffer[kVertexBlockMaxSize];
  unsigned char transposed[kVertexBlockSizeBytes];
  + size_t vertex_count_aligned = (vertex_count + kByteGroupSize - 1) & ~(kByteGroupSize - 1);
  +
  for (size_t k = 0; k < vertex_size; ++k)
  {
  - data = decodeBytes(data, data_end, buffer, (vertex_count + kByteGroupSize - 1) & ~(kByteGroupSize - 1));
  + data = decodeBytes(data, data_end, buffer, vertex_count_aligned);
  if (!data)
  return 0;
  