[mythtv] MythTV customizations to libdvdread and libdvdnav

[Scott Theisen]

I was looking at how they differ from their last merged upstream versions.
dvdnav: 
https://drive.google.com/file/d/1Hy2KUZB6UXNYp8P96CWn0HCRK38VK9rs/view?usp=sharing
dvdread: 
https://drive.google.com/file/d/1ekcOahmSHv8ywitZizJFqIDrmTIiTYyN/view?usp=sharing

Does anyone know if these changes are still necessary?

They appear to be:
Add the ability to playback remote DVD and Blu-ray directory images a… 
https://github.com/MythTV/mythtv/commit/3af3489357da268916c05f00b202f27c92508545 


RingBuffer: Play encrypted dvd's and iso images from storage groups 
https://github.com/MythTV/mythtv/commit/1ff446ad093064ff365d60561224231b6c3e7c5b 


libdvdnav only:
Implement DVD bookmarks by saving and restoring the full DVD VM's sta… 
https://github.com/MythTV/mythtv/commit/4f023d72227d6f3be654fc1615483290674c288d 



However, libbluray appears to have been unmodified since Move Bluray 
storage group handling out of libbluray and into our code. 
https://github.com/MythTV/mythtv/commit/99c61cc14700608a33f130c393cde4fbc04e1eaa 


Perhaps, the changes to libdvdread and libdvdnav can be similarly moved 
into the MythTV code instead?

The libdvdnav change to enable saving the VM state would probably have 
to be upstreamed, though.

Thoughts?

Scott