This has been very useful to figure out the FBConfig story for the GLX
EGL implementation.

BUG=angleproject:892

Change-Id: Ie4138dd1dd98f1450984a61317e3fc863c620ad3
Reviewed-on: https://chromium-review.googlesource.com/272371Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/272907