This patch adds handling of the EGL ANGLE platform api version display
attributes for better testing.

It makes the code more resilient by ignoring X11 errors that could crash
our program in the call to glXCreateContextAttribsARB.

It also makes sure that we always choose the most recent OpenGL version
available on the system.

BUG=angleproject:1188

Change-Id: I26e1bf6733215db6f5841b54c471f644e2b15e89
Reviewed-on: https://chromium-review.googlesource.com/309633Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Corentin Wallez <cwallez@chromium.org>