The traces that were already in the repository were converted to
snappy, then trimmed to their last frame Nrespectively, and
repacked back to brotli with quality 11.

CS, CS-source, and Portal2, didn't require any specific handling and
were trimmed by running

   apitrace gltrim -f N -o $f-v2.trace $f.trace

For Half Life 2 additional setup frames were needed and the
trim command command was

   apitrace gltrim -s 243-476 -f490 $f-v2.trace $f.trace

The resulting traces all consist of a setup frame an the final
frame from the original trace.

Signed-off-by: Gert Wollny <gert.wollny@collybora.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <!30>