Backport of "glmixer: Add GL_SYNC_META option to bufferpool" into 1.24
requested to merge gstreamer-backport-bot/gstreamer:mr-6756-backport-into-1.24-Add-GL_SYNC_META-api-to-allocation-query into 1.24
Backport of !6756 (merged) "glmixer: Add GL_SYNC_META option to bufferpool".
Commits:
- a92167ea glmixer: Add GL_SYNC_META option to bufferpool