Decoder accesses deleted SPS decoding Multilayer stream (part2)

[nikolai.shostak]

In continuation of #1554

When there are more than 2 layers, xWriteOutput() may access deleted SPS as well. So, it should use m_chromaFormatIDC saved in Picture object

In addition to it.

1) xWriteOutput() accesses potentially deleted SPS here:

  const SPS* activeSPS = (pcListPic->front()->cs->sps);
  uint32_t maxNrSublayers = activeSPS->getMaxTLayers();

This is safe in case of single-layer OLS only.

2) DecApp::decode() uses this pattern in multiple places:

  pcListPic->front()->cs->sps->getBitDepths();

In case of Multi-layer OLS, this SPS can be deleted.
I suggest to save BitDepths in Picture object as well.

MR is coming.