GL: Put commas between vendor and renderer strings.
GL: Put commas between vendor and renderer strings.

This allows ANGLE's GL backend's renderer string to be parseable.

BUG=882580

Change-Id: I834dc236b1b72edcbc5285bcca4a1962f95f490d
Reviewed-on: https://chromium-review.googlesource.com/c/1337463
Reviewed-by: Jamie Madill <7e492b4f1c8458024932de3ba475cbf015424c30@chromium.org>
Commit-Queue: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle