glbench: remove unit from .png file names

Prepending the benchmark unit to pixel readback file name was serving
no other purpose than to match the "testname" which also used to have
the unit prepended.

This change looks scarier than it is... it is mostly just file names
change, plus the corresponding .html and .txt imagename indexes, some
documentation, and a one line change to testbase.cc to stop prepending
unit_ to the generated image names.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>

BUG=none
TEST=test_that graphics_GLBench

Change-Id: I2e0810a4bc5c4b9dcd69413f05f5fa3d4e27eb58
Reviewed-on: https://chromium-review.googlesource.com/202888
Tested-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Commit-Queue: Daniel Kurtz <djkurtz@chromium.org>
216 files changed
tree: 4515b7f3df6362d8d0228e559fd6d2a3a11a4fbe
  1. glbench_knownbad_images/
  2. glbench_reference_images/
  3. README