[bs_parser_hevc] Support for I-slices with enabled IBC
[bs_parser_hevc] Support for I-slices with enabled IBC

Standard allows I-slices with enabled IBC, which is effectively ignored.
Skip ref-list modification for I-slices to avoid exception.

Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK,Intel-Media-SDK/MediaSDK