Fix skipShortTermRefPicSets in ts/H265Reader

[pengbins]

This PR try to resolve issue androidx/media#303

The attached media file can be played by ffplay, but cause ExoPlayer throw exception during parse the SPS header from skipShortTermRefPicSets.

skipShortTermRefPicSets is a simplified version which only used for parse SPS. The full version see H.265/HEVC 7.3.7. and FFmpeg code and HM code .

There are two bugs (or over-simplified) in the function skipShortTermRefPicSets, which cause this issue:

1. Should read use_delta_flag[j] when used_by_curr_pic_flag[j] is 0.
2. NumDeltaPocs in each RefPicSet(RPS) maybe different, previousNumDeltaPocs needs to be updated for predicted RPS too.

Although each RPS always predict from previous one, but the number of deltaPocs of current RPS depends on the values of use_delta_flag[j] and used_by_curr_pic_flag[j]. Currently previousNumDeltaPocs only updated for non-predicted RPS.

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[icbaker]

Closing in favour of androidx/media#313 (we are only accepting new PRs on the androidx/media Github project).