Backport of "libs: h265enc: Set VA_PICTURE_HEVC_INVALID flag for invalid picture" into 1.16
Backport of !271 (merged) "libs: h265enc: Set VA_PICTURE_HEVC_INVALID flag for invalid picture".
Commits:
- 2aec396e libs: h265enc: Set VA_PICTURE_HEVC_INVALID flag for invalid picture