The current libwebm integration test samples contain `libwebm-0.2.1`
however we have updated to a newer version of libwebm so we need to
update the samples.
As of `libwebm-0.3.0` this signature has been frozen so we won't have to
do this again.
Instead of using the test file's index in a list to create the output
name, use the original filename and the descriptor.
This caused some problems with file name collisions when some tests
were using the same name. That was fixed by changing the names. This
will go away once they are transitioned to use DiffDir like the other
tests.
Change-Id: I0a4c480406705ca63fcea61c86c67d4a5f739295