(cherry picked from commit 92cfd28d2b)
The ffmpeg updates aren't build rebuilds, so I forward-pick them
from staging to master. I suspect they have important fixes.
Originally from PR #93217.
Switch the order in which the version-specific attributes are combined
with args. Otherwise, if args such as 'branch' are overridden by an
overlay or other derivation, the new value is replaced with the
original when the sets are combined with //.
@vcunat removed 2.7 and 2.6. The global version of 2.6 was unused,
and 2.7 -> 2.8 switch should be without problems by inspecting
http://abi-laboratory.pro/tracker/timeline/ffmpeg/
(only ABI changes and symbol additions)
