lowlevel-blt-bench: all bench funcs to return pix_cnt

The bench_* functions, that did not already do it, are modified to
return the number of pixels processed during the benchmark. This moves
the computation to the site that actually determines the number, and
simplifies bench_composite() a bit.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Ben Avison <bavison@riscosopen.org>
1 file changed