Backport of "ass: avoid infinite unref loop with bad data" into 1.16
requested to merge tpm/gst-plugins-bad:backport-mr-751-into-1.16-fix-assrender-infinite-unref-loop into 1.16
Backport of !751 (merged) "ass: avoid infinite unref loop with bad data".
Commits:
- 84718775 ass: avoid infinite unref loop with bad data