codecs: h265: Fix dependent slice header

Some subclass require per slice information to operate (rather then first slice). The dependent slice header don't are missing important information that is expected during reference list creation. This fixes it using the same method used in gstreamer-vaapi (the variable to do so was already there, just not implemented).

This also include some minor fixes in the parser and the decoder.

added 2 commits

• 76561be9 - h265decoder: Prevent possible infinite loop
• b2bf9918 - h265decoder: Complete dependent slice header

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works for me, thanks!

assigned to @gstreamer-merge-bot

unassigned @gstreamer-merge-bot

mentioned in issue #1446

mentioned in commit ndufresne/gst-plugins-bad@5540258f

mentioned in commit ndufresne/gst-plugins-bad@f7079971

mentioned in commit ndufresne/gst-plugins-bad@cecd8491

resolved all threads

mentioned in issue #1447 (moved)

mentioned in issue gstreamer-vaapi#282

added 6 commits

• b2bf9918...4e4c26af - 3 commits from branch gstreamer:master
• 5540258f - h265parse: Add missing const qualifier
• f7079971 - h265decoder: Prevent possible infinite loop
• cecd8491 - h265decoder: Complete dependent slice header

Compare with previous version

assigned to @gstreamer-merge-bot

assigned to @ndufresne and unassigned @gstreamer-merge-bot

I couldn't merge this branch: CI failed!

assigned to @gstreamer-merge-bot and unassigned @ndufresne

mentioned in commit ndufresne/gst-plugins-bad@2e2e93c3

mentioned in commit ndufresne/gst-plugins-bad@e3fb5f89